[vi]: sankoku, iwakoku

Google N-gram Corpus Counts
╭─ーーーーー─┬─────────┬───────╮
│ 口直し　　 │ 137,420 │ 96.5% │
│ 口なおし　 │   2,664 │  1.9% │ - add, sK
│ 口直　　　 │     816 │  0.6% │
│ クチ直し　 │     293 │  0.2% │
│ くち直し　 │     166 │  0.1% │
│ くちなおし │   1,039 │  0.7% │
╰─ーーーーー─┴─────────┴───────╯

@@ -5,0 +6,4 @@
+</k_ele>
+<k_ele>
+<keb>口なおし</keb>
+<ke_inf>&sK;</ke_inf>
@@ -12,0 +17 @@
+<pos>&vi;</pos>

daijr koj

Also palate cleanser itself

@@ -16,0 +16,6 @@
+<sense>
+<pos>&n;</pos>
+<gloss>palate cleanser</gloss>
+<gloss>intermezzo</gloss>
+<gloss g_type="expl">dish or beverage to cleanse one's palate between dishes of a meal</gloss>
+</sense>

@@ -12,1 +12,3 @@
-<gloss>removing a bad taste, cleansing the palate</gloss>
+<pos>&vs;</pos>
+<gloss>removing a bad taste</gloss>
+<gloss>cleansing one's palate</gloss>

Yes, the kokugos are clear on this.

https://dictionary.goo.ne.jp/word/晴曇/#jn-122449

せい‐どん【晴曇】= はれとくもり。晴天と曇天。

Making it more clear that the two are exclusive, rather than meant to describe a weather wich is cloudy but pleasant.

-> Note: this as been badly translated in the french glossary section, probably from the english.
-> "beau temps avec des nuages?" = "nice weather with clouds ?"

Should probably add references metadata to the the entries:
seq: 1376550 = 晴天 = fine weather
seq: 1457570 = 曇天 = cloudy weather

@@ -12 +12 @@
-<gloss>fine weather and cloudy</gloss>
+<gloss>fine weather and cloudy weather</gloss>

gg5, luminous, wisdom, daijr

@@ -12 +11,0 @@
-<ke_inf>&rK;</ke_inf>
@@ -22 +21,2 @@
-<gloss>retirement age</gloss>
+<gloss>(compulsory) retirement age</gloss>
+<gloss>age limit</gloss>
@@ -28,2 +28,3 @@
-<xref type="see" seq="1943160">定年退職・ていねんたいしょく</xref>
-<gloss>(compulsory) retirement (e.g. on reaching the age of 65)</gloss>
+<xref type="see" seq="1943160">定年退職</xref>
+<gloss>(compulsory) retirement (on reaching retirement age)</gloss>
+<gloss>mandatory retirement</gloss>
@@ -31,0 +33 @@
+<stagk>停年</stagk>
@@ -33,2 +35,2 @@
-<misc>&arch;</misc>
-<gloss>years of service in a military rank before eligibility for promotion</gloss>
+<misc>&hist;</misc>
+<gloss>minimum years of service at a particular rank before eligibility for promotion (in the Imperial Japanese Army and Navy)</gloss>

sankoku: 名・自さ。退官・退職することになっている、一定のとし（になること）
trans. mine: In the state resulting from having to retire (through actions out of one's control), at a prescribed age

daijs confirms [1],[2], [vs]:
［名］(スル)法規・規則により、一定の年齢到達を事由に退官・退職することになっている年齢。(sense 1)また、退官・退職すること(sense 2)。「―を迎える」

定年後	532914	  
定年後の再雇用	181396	

定年	2240583	
定年した	4286	  
定年したら	2306	  
定年した後	382	  
定年したばかり	373	  
定年した人	320
定年したばかりな	249	  
定年したばかりなの	247	  
定年した父	173	 

Compare:
定年した人	320
定年になった人	364	  


高齢人材は「お荷物」か「助っ人」か　タニタ、セブンの選択
https://business.nikkei.com/atcl/NBD/19/special/00735/
今から11年前、タニタ総研は60歳で定年した後の再雇用の受け皿会社として設立。定年を迎えた社員の再雇用の受け皿として、子会社や関連会社を活用する会社は多い。

I suspect this evolved as a shorthand for the xref (and similar related terms).

Far more than the not-so-common する usage, you can see from the n-grams on
定年後の再雇用 181396

that 定年後 means "after retirement/after having to retire", not "after reaching retirement age". 

Perhaps [1] should add (compulsory) as well.

Looking at a number of reverso examples (which lean heavily toward "retirement age"), I don't think [1] and [2] are the same sense, related though they may be. 
[1] is a number. "retirement age is 60, 65, 70"... "retire before reaching retirement age".  It's a noun with no straightforward する verb equivalent.
[2] is the act of retiring/having been retired at a fixed age.

@@ -25,0 +26,7 @@
+<pos>&vs;</pos>
+<pos>&vi;</pos>
+<xref type="see" seq="1943160">定年退職・ていねんたいしょく</xref>
+<gloss>(compulsory) retirement (e.g. on reaching the age of 65)</gloss>
+</sense>
+<sense>
+<pos>&n;</pos>

定年	2241679
停年	16082 (mk)

@@ -11,0 +12 @@
+<ke_inf>&rK;</ke_inf>

gg5, prog, daij, reverso

@@ -20,3 +20,3 @@
-<xref type="ant" seq="1619510">退場・1</xref>
-<gloss>entry (on stage)</gloss>
-<gloss>appearance (on screen)</gloss>
+<xref type="ant" seq="1619510">退場・2</xref>
+<gloss>entrance (on the stage)</gloss>
+<gloss>appearance (in a book, film, etc.)</gloss>
@@ -28,2 +28,5 @@
-<gloss>entrance</gloss>
-<gloss>introduction (into a market)</gloss>
+<gloss>appearance (on the scene)</gloss>
+<gloss>arrival (on the market)</gloss>
+<gloss>emergence</gloss>
+<gloss>introduction</gloss>
+<gloss>advent</gloss>

mk

@@ -18,0 +19 @@
+<pos>&vi;</pos>
@@ -25,0 +27 @@
+<pos>&vi;</pos>

They clean themselves up a bit on approval. Don't worry, we'll keep an eye on them.

Please help me clean up the cross-references!

@@ -18,0 +19 @@
+<xref type="ant" seq="1619510">退場・1</xref>
@@ -20 +20,0 @@
-<xref type="ant" seq="1619510">退場・1</xref>

daij, meikyo, smk

@@ -14,0 +15,5 @@
+<sense>
+<pos>&n;</pos>
+<xref type="see" seq="1767800">死に顔</xref>
+<gloss>face of a dead person</gloss>
+</sense>

@@ -12 +12 @@
-<gloss>look of death</gloss>
+<gloss>look of death (in one's face)</gloss>

〈辻／つじ／ツジ〉〈斬（り）／切（り）／ぎり／ギリ〉

Google N-gram Corpus Counts
╭─ーーーー─┬────────┬───────╮
│ 辻斬り　 │ 30,433 │ 84.8% │
│ 辻斬　　 │  1,769 │  4.9% │
│ 辻切り　 │  1,340 │  3.7% │ - add, sK (sankoku)
│ 辻切　　 │    144 │  0.4% │
│ つじ切り │    102 │  0.3% │
│ 辻ぎり　 │     57 │  0.2% │
│ つじぎり │  1,951 │  5.4% │
│ ツジギリ │     91 │  0.3% │
╰─ーーーー─┴────────┴───────╯

@@ -8,0 +9,4 @@
+</k_ele>
+<k_ele>
+<keb>辻切り</keb>
+<ke_inf>&sK;</ke_inf>

@@ -18 +18 @@
-<gloss>attacking a passerby with a sword (to tests its sharpness or one's skill)</gloss>
+<gloss>attacking a passerby with a sword (to test its sharpness or one's skill)</gloss>

gg5, daij

We usually include the "その人" meaning in the same sense if there are only a couple of glosses.
The passive usage indicates that it's transitive.

@@ -16 +16 @@
-<pos>&vi;</pos>
+<pos>&vt;</pos>
@@ -18,6 +18,2 @@
-<gloss>killing a passerby in order to test a new sword</gloss>
-</sense>
-<sense>
-<pos>&n;</pos>
-<misc>&hist;</misc>
-<gloss>one who has tested a new sword by killing a passerby</gloss>
+<gloss>attacking a passerby with a sword (to tests its sharpness or one's skill)</gloss>
+<gloss>samurai who tries out his sword on a passerby</gloss>

daijs:
昔、武士が刀剣の切れ味や自分の腕を試すために、往来で通行人を斬ったこと。また、それを行う者。特に江戸初期には禁令が出るほど横行した。

辻斬り	30433	  
辻斬りの	2967	  
辻斬りに	1880	  
辻斬りを	1618	  
辻斬りされた	891

English wikipedia, daijs, and sankoku (amazing...) all give sense [2] explicitly.  Must be a bit of romanticized imagery to have such a high ngram count... (the action itself doesn't seem to have actually been so prevalent).

sankoku says 自さ, common n-grams suru usage is passive. I guess 辻斬り is just the act of testing the sword, and doesn't actually take an object.

@@ -14,0 +15,2 @@
+<pos>&vs;</pos>
+<pos>&vi;</pos>
@@ -16,0 +19,5 @@
+</sense>
+<sense>
+<pos>&n;</pos>
+<misc>&hist;</misc>
+<gloss>one who has tested a new sword by killing a passerby</gloss>

gg5, RP, 学大辞典

@@ -11,0 +12 @@
+<gloss>kleptomania</gloss>

どうしようもない	1572389	96.7%
どうしょうもない	54199	3.3%

rare kana candidate maybe

@@ -30,0 +31,4 @@
+</r_ele>
+<r_ele>
+<reb>どうしょうもない</reb>
+<re_inf>&sk;</re_inf>

jitsuyo (どう仕様もない):「どうしようもない」の不適切な表記。漢字を用いる場合には普通「如何しようもない」などと書く。

仕様 is irregular here. The しよう in どうしようもない is the volitional form of する, not a noun. Note that daijs has 仕様もない for しょうもない but only 如何しようも無い for どうしようもない.

One more counterpoint to myself you might also consider:
どう仕様も無い[rK]
all else [sK].

This provides all of the "reasonable" kanji for the entry (如何 excluded).  I find that it can be easier to understand a long string of kana when you unambiguously understand the associated kanji form, even if the kanji are not ordinarily used.

While it's in my previous treatise somewhere, I'll just add succinctly "I agree".  Will try for some more condensed edits going forward.

I think all the kanji forms can be sK.

@@ -5,0 +6 @@
+<ke_inf>&sK;</ke_inf>
@@ -9 +10 @@
-<ke_inf>&rK;</ke_inf>
+<ke_inf>&sK;</ke_inf>

gg5, prog, luminous, wisdom
遺憾なく発揮	68,519		
如何なく発揮	15,402

The counts appear to be valid. 如何なく is very common.
I don't think we're using rK for 無い/無く in expressions.

@@ -8,2 +8,2 @@
-<keb>遺憾無く</keb>
-<ke_inf>&rK;</ke_inf>
+<keb>如何なく</keb>
+<ke_inf>&iK;</ke_inf>
@@ -12 +12 @@
-<keb>如何なく</keb>
+<keb>遺憾無く</keb>
@@ -23,0 +24,3 @@
+<gloss>fully</gloss>
+<gloss>to the full</gloss>
+<gloss>(most) satisfactorily</gloss>
@@ -26 +28,0 @@
-<gloss>fully</gloss>
@@ -28 +30 @@
-<gloss>all out</gloss>
+<gloss>perfectly</gloss>

遺憾なく	78633	53.0%
遺憾無く	3855	2.6% <- GG5, kokugos 
如何なく	17721	11.9%
如何無く	870	0.6%
いかんなく	47374	31.9%

Suggest iK moved to sK. The count for 如何なく looks odd.

@@ -8,0 +9 @@
+<ke_inf>&rK;</ke_inf>
@@ -12 +13 @@
-<ke_inf>&iK;</ke_inf>
+<ke_inf>&sK;</ke_inf>
@@ -16 +17 @@
-<ke_inf>&iK;</ke_inf>
+<ke_inf>&sK;</ke_inf>

i think the iK forms should go last

@@ -7,0 +8,3 @@
+<keb>遺憾無く</keb>
+</k_ele>
+<k_ele>
@@ -10,3 +12,0 @@
-</k_ele>
-<k_ele>
-<keb>遺憾無く</keb>

http://www.practical-japanese.com/2010/10/blog-post_7584.html
ngrams

@@ -3,0 +4,7 @@
+<k_ele>
+<keb>遺憾なく</keb>
+</k_ele>
+<k_ele>
+<keb>如何なく</keb>
+<ke_inf>&iK;</ke_inf>
+</k_ele>
@@ -8 +15,2 @@
-<keb>遺憾なく</keb>
+<keb>如何無く</keb>
+<ke_inf>&iK;</ke_inf>

Google N-gram Corpus Counts
╭─ーーーー─┬─────────┬───────╮
│ 端から　 │ 443,504 │  N/A  │ - lots of false positives
│ はなから │  74,427 │ 51.7% │
│ ハナから │  69,445 │ 48.3% │ - add, nokanji (seen in a novel)
╰─ーーーー─┴─────────┴───────╯

@@ -8,0 +9,4 @@
+</r_ele>
+<r_ele>
+<reb>ハナから</reb>
+<re_nokanji/>

Entry created

@@ -13,0 +14 @@
+<misc>&id;</misc>

Not needed.

gg5, prog
daijs: "渡りに船の申し出"

More glosses.
Is the literal translation necessary? Could add a lit. gloss.

@@ -11,0 +12,5 @@
+<pos>&n;</pos>
+<pos>&adj-no;</pos>
+<gloss>godsend</gloss>
+<gloss>lifesaver</gloss>
+<gloss>timely offer</gloss>
@@ -13 +17,0 @@
-<gloss>godsend (like a finding a ship when one needs to cross)</gloss>

Entry created

gg5
daijs: どんなであっても。どのようなことがあっても。「―連れて帰る」

Not just negative sentences.

@@ -13,2 +12,0 @@
-<pos>&adv;</pos>
-<xref type="see" seq="1466950">如何しても・1</xref>
@@ -16,2 +14,2 @@
-<s_inf>used in neg. sentences</s_inf>
-<gloss>whatever the case</gloss>
+<gloss>whatever happens</gloss>
+<gloss>no matter what</gloss>
@@ -18,0 +17,3 @@
+<gloss>in any case</gloss>
+<gloss>at all costs</gloss>
+<gloss>at any price</gloss>

どうあっても	25413	99.8%
如何あっても	43	0.2%

@@ -5,0 +6 @@
+<ke_inf>&sK;</ke_inf>

@@ -15 +15,2 @@
-<gloss>whatever the case (used in neg. sentences)</gloss>
+<s_inf>used in neg. sentences</s_inf>
+<gloss>whatever the case</gloss>

Indeed.

@@ -10 +10,2 @@
-<gloss>castling (chess)</gloss>
+<pos>&vi;</pos>
+<gloss>castling (in chess)</gloss>

jwiki www-images

@@ -8,0 +9 @@
+<pos>&vs;</pos>

To avoid any confusion.

@@ -9 +9 @@
-<gloss>castling</gloss>
+<gloss>castling (chess)</gloss>

Entry created

gg5, daijs
https://goiryoku.com/onomatopoeia/baltusabaltusa/

@@ -10,0 +11 @@
+<pos>&adv;</pos>
@@ -11,0 +13,6 @@
+<misc>&on-mim;</misc>
+<gloss>(cutting down) one after another</gloss>
+<gloss>left and right</gloss>
+<gloss>in quick succession</gloss>
+</sense>
+<sense>
@@ -12,0 +20 @@
+<pos>&adv-to;</pos>
@@ -14,2 +22 @@
-<gloss>rapidly</gloss>
-<gloss>flapping wings</gloss>
+<gloss>flapping (of a large bird's wings)</gloss>

Google N-gram Corpus Counts
╭─ーーーーーー─┬────────┬───────╮
│ バッサバッサ │ 31,240 │ 68.4% │ - add
│ ばっさばっさ │ 14,414 │ 31.6% │
╰─ーーーーーー─┴────────┴───────╯

@@ -3,0 +4,3 @@
+<r_ele>
+<reb>バッサバッサ</reb>
+</r_ele>

I find that use of 派 a bit enigmatic.

daijs:（見た目や、個性的なだけではなく）すぐれた演技力をもつ役者。

Don't forget the 派.

@@ -12,3 +12,2 @@
-<pos>&adj-no;</pos>
-<gloss>acting skill</gloss>
-<gloss>performing ability</gloss>
+<gloss>actor with excellent acting abilities (as opposed to just good looks)</gloss>
+<gloss>actor of real skill</gloss>

GG5: あの俳優は若いがなかなかの演技派だ. Young though he is, he's 「an actor of real skill [a real actor]. | He's young, but he certainly knows how to act.
Reverso

I don't think "relying on" works here. I think simpler glosses work.

@@ -13 +13,2 @@
-<gloss>relying on acting skills (rather than good looks, etc.; of an actor)</gloss>
+<gloss>acting skill</gloss>
+<gloss>performing ability</gloss>

@@ -13 +13 @@
-<gloss>(actor) relying on acting skills (rather than good looks, etc.)</gloss>
+<gloss>relying on acting skills (rather than good looks, etc.; of an actor)</gloss>

GG5, 新和英中辞典

@@ -13,1 +13,1 @@
-<gloss>(of an actor) relying on acting (rather than good looks, etc.)</gloss>
+<gloss>(actor) relying on acting skills (rather than good looks, etc.)</gloss>

@@ -8,0 +9,3 @@
+</r_ele>
+<r_ele>
+<reb>ふー</reb>

https://www.collinsdictionary.com/us/dictionary/english/woohoo

@@ -20 +20 @@
-<gloss>wohoo</gloss>
+<gloss>woohoo</gloss>

@@ -12 +12 @@
-<xref type="see" seq="1010970">ふうふう・1</xref>
+<xref type="see" seq="1010970">ふうふう・2</xref>

@@ -12 +12 @@
-<xref type="see" seq="1010970">ふうふう</xref>
+<xref type="see" seq="1010970">ふうふう・1</xref>

プラスマイナスゼロ	30643	93.7%
プラス・マイナス・ゼロ	2063	6.3%

Maybe this.

@@ -11,0 +12 @@
+<re_nokanji/>

@@ -3,0 +4,3 @@
+<k_ele>
+<keb>プラスマイナス０</keb>
+</k_ele>
@@ -11,0 +15 @@
+<misc>&uk;</misc>

Aligning.

@@ -13,2 +12,0 @@
-<gloss>no profit</gloss>
-<gloss>no gain</gloss>
@@ -15,0 +14 @@
+<gloss>coming out even</gloss>

GG5, ルミナス

Also a company name.

@@ -6,0 +7,3 @@
+<r_ele>
+<reb>プラス・マイナス・ゼロ</reb>
+</r_ele>
@@ -9 +12,4 @@
-<gloss>No loss or gain</gloss>
+<lsource ls_wasei="y">plus minus zero</lsource>
+<gloss>no profit</gloss>
+<gloss>no gain</gloss>
+<gloss>no loss or gain</gloss>

http://thesaurus.weblio.jp/content/プラ�
%9E%E3%82%A4%E3%82%BC%E3%83%AD

損も得もしない

窃盗強迫	        0		
クレプトマニア	354		
窃盗癖	        866		
盗癖	        5,108		
窃盗症	        72

This gets barely any web hits.

@@ -11,0 +12,2 @@
+<xref type="see" seq="1448540">盗癖</xref>
+<misc>&rare;</misc>

mentioned in both daijs and nipp's クレプトマニア entries

@@ -3,0 +4,3 @@
+<k_ele>
+<keb>プラマイ０</keb>
+</k_ele>
@@ -10,0 +14 @@
+<misc>&uk;</misc>

I agree. I'll align them.

@@ -11,2 +10,0 @@
-<gloss>no profit</gloss>
-<gloss>no gain</gloss>
@@ -13,0 +12 @@
+<gloss>coming out even</gloss>

Rather, I think both entries should be aligned to have 'coming out even' as a gloss. It's useful and not as obvious when looking at the word itself.

Aligning.

@@ -11 +10,0 @@
-<gloss>coming out even</gloss>
@@ -12,0 +12,2 @@
+<gloss>no gain</gloss>
+<gloss>no loss or gain</gloss>

釣り鐘墨	  No matches　 - daijr/s

We don't usually include a romanised gloss unless it's somewhat common in English.
I don't think a specialised term like this needs a rare tag.

@@ -5,0 +6,3 @@
+</k_ele>
+<k_ele>
+<keb>釣り鐘墨</keb>
@@ -12,2 +15 @@
-<misc>&rare;</misc>
-<gloss>tsurigane-zumi (ink-stone shaped like a bell)</gloss>
+<gloss>bell-shaped inkstick made from pine soot and wax</gloss>

釣鐘墨	63

Shows up like this in calligraphy supply lists.

@@ -12 +12,2 @@
-<gloss>bell-shaped ink</gloss>
+<misc>&rare;</misc>
+<gloss>tsurigane-zumi (ink-stone shaped like a bell)</gloss>

三省堂　スーパー大辞林; デジタル大辞泉; 広辞苑 第六版

gg5, RP
上拍	137		
弱拍	2,518

Been quiet for a time, so here's an exapansion.
3 of the "Five types of women you’ll meet in Japan" are already entries. I'll propose an entry for the last.

@@ -13 +13 @@
-<gloss>Minato girl</gloss>
+<gloss>Minato girl (young woman who likes spending time in fancy neighbourhoods)</gloss>

https://fromjapan.info/topics-about-five-types-of-women-you-will-meet-in-japan/

I see we have an entry for 肉食女子.

https://www.ohkuraya.co.jp/buy/column/article/3128
https://sumai-step.com/column/article/28542/
https://www.polus-mind.jp/column/house_comparison/station.html

It gets plenty of web hits. Worth having.
I think "far" is fine.

@@ -10,0 +11 @@
+<pos>&adj-no;</pos>
@@ -12 +12,0 @@
-<pos>&adj-no;</pos>
@@ -15 +15 @@
-<gloss>(being) distant from a station</gloss>
+<gloss>far from a station</gloss>

駅遠	3090
駅遠の	543

Hard to verify. It's not a single morpheme so the counts are risky. It seems a jokey alternative to 駅近, so maybe it's worth having.

@@ -10,0 +11 @@
+<pos>&n;</pos>
@@ -12 +12,0 @@
-<pos>&n;</pos>
@@ -15 +15 @@
-<gloss>far from a (train) station</gloss>
+<gloss>(being) distant from a station</gloss>

It should probably be distinguished from 退職者.

@@ -12 +12 @@
-<gloss>retired person</gloss>
+<gloss>retired person (who has reached retirement age)</gloss>

gg5, luminous
G n-grams: 47161

OK

https://en.wiktionary.org/wiki/broadside#Noun

"Broadside" also refers to the guns themselves.

@@ -14 +14 @@
-<gloss>broadside</gloss>
+<gloss>broadside (firing of all the guns on one side of a warship)</gloss>

片舷斉射	213
新編英和活用大辞典, RP

No need to explain the gloss.

@@ -11,0 +12 @@
+<field>&mil;</field>
@@ -14 +14,0 @@
-<gloss g_type="expl">a firing of all guns from one side of a warship</gloss>

Oxford Languages · Learn more
noun: broadside; plural noun: broadsides
1.a fierce verbal attack.
2.
HISTORICAL
a. a firing of all the guns from one side of a warship. <- 片舷斉射 is only this one
b. the set of guns which can fire on each side of a warship.
c. the side of a ship above the water between the bow and quarter.

Actually have several reverso instances of this one.  This seems to be the correct term for the battleship usage.
https://context.reverso.net/翻訳/英語-日本語/broadside#片舷斉射

https://ejje.weblio.jp/content/broadside
舷側、片舷斉射、(悪口の)一斉攻撃

研究社 新英和中辞典での「broadside」の意味
broadside
アクセント・音節bróad・sìde 発音を聞く
1【航海, 海語】 舷側.
2a片舷斉射.
b(悪口の)一斉攻撃.

This blog shows usage and confirms the reading. 
https://ameblo.jp/economirai88/entry-12648261685.html
戦艦ドレッドノートの基本諸元は、満載排水量２万１千トン余り、３０ｃｍ連装主砲５基搭載、最大装甲厚約２８ｃｍ、最大速力時速２１ノットでありました。主砲塔２番基、３番基は、艦橋横近辺に平行に備え付けられましたが、片舷（へんげん）斉射（せいしゃ）の場合には、４基８門の砲が敵を狙い撃つ能力を備えています。

https://www.wordreference.com/enja/broadside
broadside n	(military: gun attack from the side)	片舷斉射 名
 	The battleship fired a broadside on the enemy ship.
 

Here is a completely modern manga reference. If the subject is historic naval warfare, this seems to be a relevant term.
https://www.sbcr.jp/product/4797356328/
あなたのハートに片舷斉射！ 男女比 １：２００の船上で繰り広げられる「ボーイ・ミーツ・ガールズ」ストーリー！！


34 yourei examples:
https://yourei.jp/片舷斉射

Also verifies the へんげん reading for the 1st half (with matches the 1940s U.S. Military Reference):
nipponica. 海戦（海上で行う戦闘） maritime war
https://kotobank.jp/word/海戦(海上で行う戦闘)-1515671
...戦術運動や片舷(へんげん)斉射などをもって...

Not trying to remove entries just for the sake of it.  

片舷斉射 entry was the most common form I found on the now-deleted 半舷砲 entry. 

reverso translates this as "broadside", and also doesn't seem to have any better Japanese translations for broadside in reference to firing guns from a battleship.

if you search google for "片舷斉射" and "broadside" (or "fire a broadside") together,  you'll see this noted in various references.

dictionary references report this as をする, and examples also use を行う, neither of which we have notes for. (ngrams agree)

deleted reference was "broadside fire", but it appears that the english gloss should just be "broadside", with 片舷斉射をする becoming "fire a broadside". The simple gloss would then need some clarification in an [expl] or parens. The [expl] feels like the most readily comprehensible approach, but maybe is more verbose than we'd like.

More general and figurative uses of "broadside" appears to be handled by 一斉攻撃. ("b(悪口の)一斉攻撃.").  

I initially simplified "a firing of all guns" to "firing all guns".... but I guess a "broadside" is in fact a single volley.

https://ja.wikipedia.org/wiki/アンパッサン
RP, 世界大百科
G n-grams: 665

Important term in chess.