A baby chews on a teething ring.
teething ring definition by Webster's New World
Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio. Used by arrangement with John Wiley & Sons, Inc.
a ring of ivory, plastic, rubber, etc., for teething babies to bite on
teething ring definition by American Heritage Dictionary
A ring of hard plastic or rubber upon which a teething baby can bite.