画龙点睛
huà lóng diǎn jīng · HSK 7
fig. to add the vital finishing touch
🐉👁️ 画 paint + 龙 dragon + 点 dot + 睛 eye = paint a dragon, then dot its eyes
From a tale of a painter whose dragons stayed lifeless until he added the eyes, then they flew off. So it means the small final touch that brings the whole thing to life, or the key words that clinch a point.
画 — hand 一 + field 田 + frame 凵
Originally a pictograph of a hand holding a brush drawing boundaries around a field, depicting the act of marking out land. The top once showed a brush (聿), and 田 represents the field being divided. Over time it came to mean 'to draw, paint' and also 'a stroke' in characters.
龙 — simplified form of 龍; phonetic-pictographic
龙 is the simplified form of the traditional 龍, an ancient pictograph depicting a serpentine dragon with a crested head, scaly body, and curling tail. In oracle bone script it was clearly drawn as a mythical reptile. The character has always meant 'dragon', a powerful and auspicious creature in Chinese culture.
点 — fire radical 灬 + 占 (zhān, phonetic)
Originally written 點, a semantic-phonetic compound: 黑 (black) gave the meaning 'small black mark or dot' while 占 supplied the sound. It first referred to ink spots, then extended to 'point, drop, a little,' and verbs like 'to mark' or 'to light (a fire),' reflected in the simplified form's 灬 (fire) component.