After food (usually meat) has been sautéed and the food and excess fat removed from the pan, deglazing is done by heating a small amount of liquid in the pan and stirring to loosen browned bits of food on the bottom. The liquid used is most often wine or stock. The resultant mixture often becomes a base for a sauce to accompany the food cooked in the pan.
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.