双向
shuāngxiàng · HSK 7
two-sided
↔️ 双向 = 双 (double, a pair) + 向 (direction) = going both directions
双 is the pair/double character (think of 双 as two hands side by side); 向 means direction or facing toward. Stick them together and you get traffic that runs both ways: two-sided, bidirectional.
双 — two 又 (right hands) side by side
Originally written 雙 with two 隹 (short-tailed birds) over 又 (hand), depicting a pair of birds held in one hand, hence 'pair' or 'two'. The modern simplified form 双 keeps just two 又 hands side by side as a visual shorthand for 'a pair'. Meaning broadened to 'double' or 'even-numbered'.
向 — roof 宀 + mouth 口
Originally a pictograph of a house with a north-facing window, showing an opening in a wall under a roof. The early meaning was 'north window,' which extended to 'the direction something faces,' then broadly to 'toward' or 'direction.' The modern shape simplified the window into 口.