noun
sea urchin
Refers to the living animal or the whole creature.
磯でうにを見つけた。
I found a sea urchin on the rocky shore.
noun
sea urchin roe; uni (as food)
Refers to the edible gonads, often served as sushi or sashimi. When written in kanji, 雲丹 is sometimes used.
新鮮なウニの軍艦巻きを食べたい。
I want to eat fresh uni gunkan-maki.
Rare kanji form used specifically for the food sense (seasoned sea urchin eggs).
Rare kanji form; not commonly used.
Rare kanji form; not commonly used.
The origin is uncertain. The word is native Japanese, and the kanji forms are jukujikun (special readings) assigned based on meaning.