As a noun 侧 means 'side': 左侧 (left side), 右侧 (right side). As a verb it means 'to lean / incline', as in 侧耳倾听 (to cock one's ear and listen). Compare 侧面 (side / profile) and 侧重 (to emphasize).
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An old reading zhāi survives only in the dialectal phrase 侧歪 ('lopsided, tilted'). It has no modern productive compounds; read cè everywhere in standard Chinese.
Person radical on the left. 侧 means 'side, lean to one side, sidelong glance', all human-spatial concepts; to stand 侧身 is to turn one's body sideways. The same radical anchors 你, 他, 体, and 仁.
Right side 则 supplies the sound: zé drifted to cè with a regular tone-and-onset shift. 则 itself shows a vessel beside a knife 刂, 'rules cut into bronze'. The same phonetic drives 测, 厕, and 恻, a tight cè/zé family.
