Tom's pupils are dilated.

How dilated is her cervix?

She's having contractions. How dilated is her cervix?

One eye is dilated.

Her eyes are dilated.

My eyes were dilated.

Roman women would dilate their pupils with belladonna because they believed this made them more attractive. Eye doctors still use belladonna during eye exams.

Tom's pupils became dilated.

I hate the drops doctors use to dilate my eyes for an eye exam.