胖的反义词用英文怎么说

"胖"的反义词是"瘦"。

"瘦"的英文是 "thin"，来源于古英语 "þynne"。

例句1：

He's thin, but he's not weak. (他很瘦，但不虚弱。)

例句2:

She's always been thin, but she's started to put on weight. (她一直很瘦，但最近开始长胖了。)

例句3:

He was thin and frail after his illness. (他生病后变得瘦弱无力。)