必
bì · HSK 5
certainly
心 (heart) + 丿 stroke; what the heart insists on = must, certainly
必 shows a heart 心 crossed by a slash 丿, marking something the heart firmly fixes on. That inner insistence gives the sense of must, surely, certainly. Sound bì rhymes with English be — what must be.
必 — heart 心 + slash 丿
Originally depicted a handle or marker driven through something, suggesting a fixed standard. The form was later reanalyzed as 心 (heart) with a stroke through it, reinforcing the sense of inner certainty. It came to mean 'must' or 'certainly'.