If 日 is the round sun, 月 is the moon mid-phase. Oracle bone scribes deliberately drew it as a crescent — not a full disk — to keep it visually distinct from 日. The shape encodes a quiet observation: what makes the moon "moon-like" to the human eye is precisely its waxing and waning, not its fullness. Identical across 繁體 / 新字体 / 简体.

Watch for a critical structural overlap: in compound characters, 月 doubles as the "flesh radical" (肉, ròu). When it sits on the left of a character, it almost always means body — 肝 (liver), 腸 (intestine), 肺 (lung) — even though the shape is identical to "moon". This is one of the most common false-friend traps in Hanzi/kanji study.

Mandarin: yuè, falling 4th tone. 月亮 (yuèliàng) is the everyday "moon"; 月份 (yuèfèn) is the calendar month; 一月 (yīyuè) is January. The lunar cycle quietly anchors the entire calendar vocabulary.

Japanese splits the on-reading by position: ゲツ (getsu) in 月曜日 (getsuyōbi, Monday) and 今月 (kongetsu, this month); ガツ (gatsu) in date names like 一月 (ichigatsu, January). The kun-reading つき (tsuki) is the warm everyday word — 月見 (tsukimi, moon-viewing), a centuries-old autumn ritual.

Memory aid: a tilted, slightly curved rectangle with two strokes inside — the crescent moon, not a circle.