a thing that dilates something, in particular 扩张物,尤指 ■(亦作 dilator muscle)(Anatomy)a muscle whose contraction dilates an organ or aperture, such as the pupil of the eye (剖)扩张肌 ■a surgical instrument for dilating a tube or cavity in the body (手术用的)扩张器 ■a vasodilatory drug 血管舒张药物