當

Phono-semantic compound:

田 (밭 전, “field”) — phonetic element, giving sound.

⿱火月口 (fire, moon, mouth cluster) — semantic reinforcement, often interpreted as brightness/clarity and balance.

Together they suggest “to face directly, to correspond, to be appropriate.”

Originally carried the sense of to face / to be opposite.

Later meanings expanded to “to be appropriate,” “to undertake a role,” and “ought to, should.”

當然 (당연) — of course, naturally

當時 (당시) — at that time

當日 (당일) — the very day

擔當 (담당) — to take responsibility

適當 (적당) — appropriate, suitable

抵當 (저당) — to mortgage, to pawn

Also used as a measure word in Chinese (for occurrences, e.g. 一當).

Polyphonic in Mandarin:

dāng → to act as, should, proper, at (a place or time).

dàng → to regard as, to pawn, suitable, to be fooled.