適切
てきせつ · tekisetsu · JLPT N3 · na-adj
appropriate
適切 = suitable 適 + close-fitting 切: fits the case exactly
適 (teki) means to suit or fit, as in 快適 comfortable. 切 (setsu) usually means cut, but here it means close or pressing, as in 親切 kind. Together they describe something that fits the situation closely, which is why the word means appropriate.
切 — 七 (phonetic) + 刀 (knife radical)
切 is a semantic-phonetic compound: 刀 'knife' gives the meaning of cutting, while 七 supplies the sound. The original sense was to slice or cut with a blade. From there it extended figuratively to 'close to' (as in pressed against) and 'urgent/earnest', as in 切实.