Know how to use "fewer" and "less"? Find out.
dilator di·la·tor (dī-lā'tər, dī'lā'-, dĭ-lā'-)
An instrument or a substance for enlarging a cavity, canal, blood vessel, or opening.
A muscle that dilates an orifice or a body part, such as a blood vessel or the pupil of the eye. Also called dilatator.