double standard

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

• noun A set of principles permitting greater opportunity or liberty to one than to another, especially the granting of greater sexual freedom to men than to women.

from The Century Dictionary.

• That may be registered in two classes: applied to cattle. Thus the double-standard polled Durhams may be registered as shorthorns or as polled Durhams.

from the GNU version of the Collaborative International Dictionary of English.

• noun a standard or set of principles governing conduct, which is applied more stringently or differently to one group of people than to another; -- used especially of standards of sexual behavior that condemn behavior on the part of women that is condoned or not condemned when exhibited by men.

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

• noun The situation of two or more groups, one of whom is tacitly excused from following a standard generally regarded as applying to all groups.

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

• noun an ethical or moral code that applies more strictly to one group than to another