@@ -12,3 +12,3 @@
-<xref type="see" seq="2147030">上弦の月・じょうげんのつき</xref>
-<xref type="see" seq="1184860">下弦の月・かげんのつき</xref>
-<xref type="see" seq="1583170">半月・はんげつ・1</xref>
+<xref type="see" seq="2147030">上弦の月</xref>
+<xref type="see" seq="1184860">下弦の月</xref>
+<xref type="see" seq="1583170">半月・1</xref>

Happy to leave cresent off this one, although some JEs have it.

hyphen, you learn something every day...

@@ -17 +17 @@
-<gloss>half moon</gloss>
+<gloss>half-moon</gloss>

Scroll down, picture of all moon phases and associated terms
https://www.arachina.com/lifestyle/moon-calendar-2022-march.htm
Here is what it says:
New Moon (0%): 新月、朔月
Waxing? Crecent: 三日月、眉月
Half:  上弦の月、引張り月、
2/3rds: 十三夜
Full: 満月、十五夜、望月
Waning? 2/3rds: 居待月
2/3rds: 二十三夜、下弦の月、下の弓張り、
WaningCrescent；下弦後の三日月、有明の月

The "bow" moons, 弦 and 引 invoke the image of a bow with a taught bowstring

Here's a picture showing that imagery:
https://weathernews.jp/s/topics/202005/260335/

Here's a reference specifically for 弦月 as "half-moon", which includes 上弦 and 下弦 as well as 弓張り月 listed as an explicit synonym.
https://en.wiktionary.org/wiki/弦月
Appears to be a learned borrowing from Chinese 弦月 (xiányuè). First cited in a Japanese text in 1698.[1] May have been in use prior to this, considering that partial synonyms 上弦 (jōgen) and 下弦 (kagen) are attested already in the late 800s.[2][3]
弦げん月げつ • (gengetsu) ←げんげつ (gengetu)?
[from 1698] half-moon 
Synonym: 弓張り月 (yumiharizuki)

This is the first of many moon edits. Lots of apparent issues with half-moons and crescent-moons.  (Note, this term on it's own is not super-common compared to 下弦　and 上弦）。

There are so many mismarked crescent-moons that I was starting to wonder if the Japanese thought 半月 included crescents... (I believe they do not)

弦月 is apparently tied up in a popular anime character which breaks the image search. try 上弦の月 and 下弦の月 instead.

Here's another a site with diagrams specifically using various formulations of 弦月
https://tukihosi-tan.com/moon/2004/

https://ja.wikipedia.org/wiki/弦月
弦月（げんげつ）は、半月（はんげつ）の文学的な表現である
Wikipedia xref for 弦月 is English "Half Moon".
In moon phases:
新月（朔。0°=0）
上弦（90°=7）
満月（望。180°=14）
下弦（270°=21）
半月（弦。上弦と下弦の総称） (半月 is a generic name for the waxing and waning half-moons)

nikk: either the waxing half-moon, the waning half-moon, or 弓張り月 (also a half-moon)
げん‐げつ【弦月】
〘名〙 上弦または下弦の月。ゆみはりづき。彎月(わんげつ)。

Another ref, straight to 半月:
https://kotobank.jp/word/弦月-491742
普及版 字通 「弦月」の読み・字形・画数・意味
【弦月】げんげつ
半月。
字通「弦」の項目を見る。

Since 半月 means 15 days/half-a-month, the ngrams crush this.  But I get the impression that this term in particular is common when talking about lunar cycles specifically. (I am sure 半月 is readily comprehensible though, perhaps moreso).


https://ja.wikipedia.org/wiki/弦月
英語でも、日本語での半月同様、一般的には half moon（または half-moon）というが、月相に基づく天文学用語としては quarter moon という。上弦の月は first quarter moon で、下弦の月は last quarter moon （または third quarter moon）である。

more notes on the xrefs.

@@ -12 +12,6 @@
-<gloss>crescent moon</gloss>
+<xref type="see" seq="2147030">上弦の月・じょうげんのつき</xref>
+<xref type="see" seq="2147030">上弦の月・じょうげんのつき</xref>
+<xref type="see" seq="1184860">下弦の月・かげんのつき</xref>
+<xref type="see" seq="1184860">下弦の月・かげんのつき</xref>
+<xref type="see" seq="1583170">半月・はんげつ・1</xref>
+<gloss>half moon</gloss>