合わす
あわす · awasu · JLPT N1 · verb-godan
to join together
合わす (awasu) = 'a-wasu': 'a' sounds like 'a' in 'align', and 'wasu' sounds like 'wa' (joined) plus 'su' (to do), so it means to make things join up together.
合 — 乛 (lid/roof) + 口 (mouth)
Originally a pictograph of a lidded vessel — a cover (亼) closing over an opening (口) — giving the core sense of 'come together, join, fit.' From 'fit/match' it extended to 'combine, unite, agree' and to measure-word uses. The reading hé reflects this 'joining' meaning.