一杯
いっぱい · ippai · JLPT N4 · noun
full moon
🍵 一杯 = one + cup: a cup filled to the brim is full
一 (one) + 杯 (cup). Literally one cupful, the word stretched from a brimming cup to anything full or at its limit. Sound hook: ippai ends like pie, and after a whole pie you are full. Pitch differs: iPpai = one cup, ippAI = full.
一 — single horizontal stroke
一 is one of the simplest pictographs in Chinese, depicting a single horizontal line to represent the number one. It has retained essentially the same form since oracle bone script over 3,000 years ago. By extension it also means 'first,' 'whole,' or 'same.'
杯 — wood radical 木 + 不 (phonetic)
杯 is a semantic-phonetic compound. The 木 radical signals wood, since ancient cups were carved from wood, while 不 hints at the sound. Originally written 桮, it came to mean any cup or glass regardless of material.