dilate
verb [ I or T ] uk/daɪˈleɪt/ us/ˈdaɪ.leɪt/
（使身体的一部分）扩张，展开
to (cause a part of the body to) become wider or further open
The pupils of the eyes dilate as darkness increases. 光线变暗时瞳孔就会放大。
This drug will dilate the arteries. 这种药可以扩张动脉血管。
Phrasal verb
dilate on/upon something 详述；铺陈
to write or speak about a subject for a long time
He likes to dilate upon what he thinks is wrong with the world. 他喜欢滔滔不绝地谈他所理解的世界的问题所在。