adverbial N3 common casualpolitewritten

結構 — quite / fine (no thanks)

結構・けっこう

Meaning

① ①degree: quite / fairly / rather — a decent, often surprising degree

② ②fine: fine / good enough / no thank you — sufficiency, or a polite refusal

① ①degree

このカバンは結構けっこう高たかい。

This bag is quite expensive.

② ②fine

「もう一杯いっぱいいかがですか。」「いえ、結構けっこうです。」

"Another glass?" "No, I'm fine, thank you."

① ①degree

テストは結構けっこう簡単かんたんだった。

The test was fairly easy.

週末しゅうまつはいつも結構けっこう忙いそがしい。

Weekends are usually pretty busy.

② ②fine

これで結構けっこうです。

This is fine as it is.

結構けっこうです is famously ambiguous — 'that's fine (I accept)' vs 'no thank you (I decline).' Tone, context, and gesture disambiguate; declining is the more common reading when offered something.

Jengo shows 結構 the way you actually meet it: inside real Japanese sentences, so it sticks instead of staying an abstract rule.

Sources Compiled with reference to A Dictionary of Advanced Japanese Grammar, A Dictionary of Intermediate Japanese Grammar.