di·late 
/ˈdaɪˌleɪt/ verb
di·lates; di·lat·ed; di·lat·ing /ˈdaɪˌleɪt/ verb : to become larger or wider [no obj] ▪ The drug causes the blood vessels to dilate. ▪ During labor, a woman's cervix will dilate to about 10 centimeters. [+ obj] ▪ The drug dilates the blood vessels.
dilate on/upon [phrasal verb]
dilate on/upon (something) formal : to talk about (a subject) for a long time
▪ We spent a long evening listening to him dilate on the need for tax relief.
▪ We spent a long evening listening to him dilate on the need for tax relief.
— dilated adjective [more dilated; most dilated]
▪ dilated pupils
▪ dilated pupils
— di·la·tion /daɪˈleɪʃən/ noun [noncount]
▪ dilation of the arteries
/daɪˈleɪʃən/ noun [noncount] ▪ dilation of the arteries
