プログレッシブ和英中辞典(第4版)の解説
きめこむ【決め込む】
❶〔決意する〕
いったんこうと決め込むと彼はがむしゃらに進む
Once he makes up his mind, he goes full tilt.
だんまりを決め込むなんてずるい
It's not fair to clam up like that and keep it all to yourself.
❷〔結論を出す〕
彼が犯人だと決め込むのはまだ早い
It is too early to conclude [jump to the conclusion] that he is the culprit [guilty party].
❸〔思い込む〕
彼は合格するものと決め込んでいた
He hadn't 「a doubt in the world [the slightest doubt] that he would pass the examination.
相手も自分にほれていると決め込んでいる
He assumes that the girl is also in love with him.
❹〔ふりをする〕
彼は居留守を決め込んだ
He pretended to be out.
色男を決め込んでいる
He is posing as 「a playboy [a Don Juan].