1For a flower to bloom or open — an intransitive verb describing a plant flowering in its season. Also used metaphorically, e.g., for a smile 'blooming' naturally.
庭のバラが今年もきれいに咲いた。
The roses in the garden have bloomed beautifully again this year.
春になると、公園の桜が一斉に咲く。
When spring comes, the cherry trees in the park all bloom at once.
この花は朝に咲いて、夕方には閉じてしまう。
This flower blooms in the morning and closes by evening.
彼女の顔に笑顔が咲いた瞬間、部屋の空気が和んだ。
The moment a smile bloomed on her face, the mood in the room softened.
2(Archaic) An old usage describing waves rising up white/foaming. Essentially unused in modern Japanese, appearing only in classical literature such as waka poetry.