expression, noun-modifying (irregular)
Describes someone or something that is round and fat, often in a cute or endearing way. Used prenominally to modify nouns.
丸々太った赤ちゃんが笑っている。
A chubby baby is smiling.
彼は丸々太った猫を飼っている。
He has a plump cat.
Simply means 'fat' or 'gained weight'; 丸々太った emphasizes a round, plump shape.
A more casual, onomatopoeic term for pleasantly plump; 丸々太った is more descriptive and can be used for animals and objects as well.
Compound of the adverb 丸々 (roundly, entirely) and the past form of 太る (to become fat), literally 'become round and fat'.