A basic definition of patriarchy
(based on Allan G. Johnson's The Gender Knot):
Patriarchal social structures are:
1. Male dominated--which doesn't mean that all men are powerful or all women are powerless--only that the most powerful roles in most sectors of society are held predominantly by men, and the least powerful roles are held predominantly by women
2. Organized around an obsession with control, with men elevated in the social structure because of their presumed ability to exert control (whether rationally or through violence or the threat of violence) and women devalued for their supposed lack of control--women are assumed to need men's supervision, protection, or control
3. Male identified: aspects of society and personal attributes that are highly valued are associated with men, while devalued attributes and social activities are associated with women. There is a sense of threat to the social structure of patriarchies when these gendered associations are destabilized--and the response in patriarchy is to increase the level of control, often by exerting control over women (as well as groups who are devalued by virtue of race, ethnicity, sexuality, or class).
4. Male centered: It is taken for granted that the center of attention is the natural place for men and boys, and that women should occupy the margins. Public attention is focused on men. (To test this, take a look at any daily newspaper; what do you find on the front page about men? about women?)