1To come apart at the seams; to start to rip or fray (fabric or seams).
古いセーターの袖がほころびてきた。
The sleeve of my old sweater has begun to fray.
鞄の縫い目がほころびて中身が見えそうだ。
The bag’s stitching is coming apart and you can almost see the contents.
2To begin to open; to start blooming (of flowers or buds).
梅のつぼみが春の暖かさでほころびてきた。
The plum buds have started to open in the spring warmth.
桜のつぼみがほころびるのを見るのが楽しみだ。
I look forward to seeing the cherry buds begin to open.
3To break into a smile; to have one’s face soften into a smile.
子どもの成長を見て、母の顔がほころんだ。
Seeing her child grow, the mother’s face broke into a smile.
冗談を聞いて彼の表情がほころんだ。
He smiled when he heard the joke.