随手
suí shoǔ · HSK 4
in passing
✋ 随 = follow + 手 = hand; 'follow-hand' = doing it as your hand passes by
随 means 'follow/along with' and 手 means 'hand'. Together they describe doing something casually as your hand happens to be there — conveniently, in passing, without extra effort.
随 — 辶 (walk) + 阝 (mound) + 有 phonetic
随 combines the walk radical 辶 with a phonetic component derived from 隋. The original sense is 'to follow along a path,' from the walking radical suggesting movement after someone. Over time it broadened to mean 'follow,' 'accompany,' or 'comply with.'
手 — pictograph of a hand with five fingers
手 is a pictograph showing an open hand with fingers and a wrist. Early bronze and oracle bone forms clearly depict five splayed fingers, which simplified over time into the modern shape. It keeps its original meaning of 'hand' and also serves as a radical in many characters related to hand actions.