プログレッシブ和英中辞典(第4版)の解説
ほころびる【×綻びる】
&fRoman1;〔縫い目が解ける〕come unsewn；〔衣服が〕come apart at the seams
このスーツは縫い目があちこちほころびた
Seams have 「popped open [come apart/come undone] here and there in this suit.
セーターのそで口がほころびかけた
The cuff of my sweater is raveling [unraveling].
&fRoman2;
❶〔つぼみが〕begin to open
桜がほころび始めた
The cherry blossoms have begun to bloom [open].／The cherry trees have started blooming.
❷〔顔などが〕smile
孫のかわいいしぐさに彼の顔は思わずほころんだ
He could not 「help smiling [repress a smile] at the innocent behavior of his grandchild.