cervical cap

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A small, rubber, cup-shaped contraceptive device that fits over the uterine cervix to prevent the entry of sperm.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun a small, latex or silicone, contraceptive device that fits over the cervix and stays in place either by suction, like Prentif or by surface viscosity, like Oves.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a contraceptive device consisting of a small thimble-shaped cup that is placed over the uterine cervix to prevent the entrance of spermatozoa