dilator

di·la·tor

noun \(ˈ)dī-ˈlāt-ər, də-\

Definition of DILATOR

: one that dilates: as a : an instrument for expanding a tube, duct, or cavity <a urethral dilator>—called also divulsor b : a muscle that dilates a part c : a drug (as a vasodilator) causing dilation