熟語
じゅくご · jukugo · JLPT N2 · noun
parlance
熟 = ripe/familiar + 語 = word: a fixed, well-worn phrase
Read as 熟 (ripe, mature, familiar) plus 語 (word, language). An idiom is a phrase so familiar it has ripened into one fixed unit. Kanji compounds like 熟語 are two-character words built from two morphemes.
熟 — 享 (offering) + 灬 (fire)
Originally written 孰, depicting hands offering food (享) for cooking. The fire radical 灬 was later added to emphasize cooking with heat. The core sense 'cooked' extended naturally to 'ripe,' 'familiar,' and 'skilled through repeated practice.'