副～
ふく～ · fuku～ · JLPT N2 · noun
frailty
副 = assistant: 副社長 = assistant + company president = vice president
副 means secondary or assistant, so a word after it names a second-in-command role, such as 副大統領 (vice president of a country) or 副作用 (side effect, a secondary effect).
副 — 刀 knife + 畐 (full vessel, phonetic)
A semantic-phonetic compound. The knife radical 刂 (刀) suggests cutting or splitting, while 畐 (a full jar) gives the sound. The original sense was 'to split in two,' which extended to 'secondary' or 'deputy' — something paired alongside the main one.