the bottom or lower side or surface of something 下侧;下面;底面 the butterfly's wings have a mottled brown pattern on the underside. 蝴蝶翅膀底面有棕色斑纹。 ■(figurative)the less favourable aspect of something (喻)(事物)阴暗面 the sordid underside of the glamorous 1980s. 辉煌的20世纪80年代的不光彩一面。