反対
はんたい · hantai · JLPT N4 · noun
opposition
反対 = turn back (反) + facing (対): facing the other way, so opposing
反 means reverse or anti-, as in 反日 or 反省. 対 means to face or versus, as in 対する and 3対2 scores. Reverse-facing = standing against something. Sound hook: hantai starts like anti with an h in front, h-anti = opposition.
反 — hand 又 under cliff 厂
Originally a pictograph of a hand (又) turning something over against a cliff or slope (厂), depicting the action of flipping or reversing. From this came the core meaning 'to turn over,' which extended to 'opposite,' 'contrary,' and 'rebel against.' The character is purely semantic, with no phonetic component.