adverb
carefully; thoroughly; closely
Used when examining, considering, or thinking about something with great care and attention.
よくよく考えた結果、その申し出を断ることにした。
After thinking it over very carefully, I decided to decline the offer.
この書
Please check these documents very carefully before submitting them.
adverb
Emphasizes the degree of a state or quality; often used in negative or surprising contexts.
彼がそんなことを言うなんて、よくよくのことがあったに違いない。
For him to say such a thing, something very unusual must have happened.
よくよく運が悪いとしか言いようがない。
I can only say that it's extremely bad luck.
adverb
unavoidable; have no choice; cannot be helped
Used in set expressions like よくよくのこと or よくよくの事情 to indicate that a situation is beyond one's control or leaves no alternative.
よくよくの事情がない限り、締め切りは延ばせません。
Unless there are unavoidable circumstances, we cannot extend the deadline.
彼が会社を辞めたのは、よくよくのことだったのだろう。
He must have had no choice but to quit the company.
Rare kanji spelling; not commonly used.
よく is the common adverb meaning 'well' or 'often'. よくよく is an emphatic reduplication used for careful consideration, extreme degree, or unavoidable situations.
Reduplication of よく (yoku), the adverbial form of 良い (yoi, 'good'). The repetition intensifies the meaning, leading to senses of 'very carefully', 'extremely', and 'unavoidably'.