Thick, cordlike strands of egg white that are attached to 2 sides of the yolk, thereby anchoring it in the center of the egg. The more prominent the chalazae, the fresher the egg. Chalazae don't affect the egg in any way, though some custard recipes call for straining to remove them for a smoother texture.
From The Food Lover's Companion, Fourth edition by Sharon Tyler Herbst and Ron Herbst. Copyright © 2007, 2001, 1995, 1990 by Barron's Educational Series, Inc.