反 is very productive: 反对 (to oppose), 相反 (opposite), 反正 (anyway/in any case), 反而 (on the contrary), 反复 (repeatedly), 反映 (to reflect), 反应 (reaction). As a prefix it means 'anti-': 反战 (anti-war).
Right hand radical underneath - the indexing component. Pictographic three-finger shorthand of a hand. Drives the active sense: to flip back, turn over, oppose, return - all hand-actions. Also seen in 友 (friend), 取 (take), 受 (receive).
Top-left cliff - pictures an overhanging rock face. Together with the hand below, the original picture was a hand turning over against a cliff, hence "to flip, reverse, oppose." The cliff also functions as a graphic anchor that lets the hand sit angled against it.
