Pictograph: a side view of a cut of meat with visible muscle striations. The character has barely changed since oracle bone times. Identical across 繁體 / 新字体 / 简体.

Critical fact for reading hanzi/kanji: when 肉 functions as a RADICAL inside compound characters, it morphs into 月 — visually identical to the moon character. This is one of the most common false-friend traps in CJK reading. So the 月 you see in 肝 (liver), 腸 (intestine), 肌 (skin), 腰 (waist), 胸 (chest), 脳 (brain), 背 (spine), 脈 (pulse) is NOT the moon but the FLESH-radical (肉) in disguise.

Quick rule: 月 on the LEFT of a character usually means flesh; 月 standing alone or on the right usually means moon. So 朝 (morning, with 月 on right) really has the moon; 肌 (skin, with 月 on left) really has flesh. Native speakers internalize this distinction unconsciously.

Mandarin: ròu, falling 4th tone. 肉 (ròu, meat / flesh), 牛肉 (niúròu, beef), 猪肉 (zhūròu, pork — note Mandarin standard 猪; older texts use 豚), 鸡肉 (jīròu, chicken), 鱼肉 (yúròu, fish flesh), 肉类 (ròulèi, meat varieties), 肌肉 (jīròu, muscle — same compound as discussed in 肌 entry). Note for vegetarians: 肉 in Chinese restaurant menus signals animal flesh.

Japanese: on-reading ニク (niku) is dominant — 肉 (niku, meat), 牛肉 (gyūniku, beef), 豚肉 (butaniku, pork), 鶏肉 (toriniku, chicken — uses 鶏), 焼肉 (yakiniku, Korean-style grilled meat — a major Japanese dining institution), 肉体 (nikutai, body / physical body — used in philosophical/literary contexts: 肉体派 = "physical type", 精神 vs 肉体 mind vs body). The kun-reading is largely absent — this is a fully on-reading-dominated character.

焼肉 (yakiniku, "grilled meat") is one of Japan's most popular dining out cuisines — a Korean-influenced meat-grilling tradition that became distinctly Japanese.

Memory aid: striations of muscle in a cut of meat. As a radical, it disguises itself as 月 — the moon false friend.