瘦(shòu) - thin, skinny in Mandarin

瘦 (shòu) means "thin, skinny", the ordinary word for a person or animal with little body fat: 他很瘦 (tā hěn shòu), "he's thin". Like most Mandarin adjectives it needs no linking verb, only the mild intensifier 很 (hěn) to sound natural in a plain statement.

Context decides whether 瘦 (shòu) is a compliment or a worry. Saying 你瘦了 (nǐ shòu le), "you've got thinner", to someone is common and usually welcome, while a doctor or a worried relative saying 你太瘦了 (nǐ tài shòu le), "you're too thin", flags the opposite concern - being underweight rather than trim.

瘦 (shòu) also describes clothes cut close to the body: 这条裤子很瘦 (zhè tiáo kùzi hěn shòu), "these trousers are slim-fit / tight", the same idea English borrows into "skinny jeans". Its natural opposite for people is 胖 (pàng, "fat"), and for clothes is 肥 (féi) or 宽松 (kuānsōng, "loose-fitting").