I think most states have gender-free definitions of rape. For example, from the Virginia criminal code:
Section 18.2-61 Rape.
A. If any person has sexual intercourse with a complaining witness who is not his or her spouse or causes a complaining witness, whether or not his or her spouse, to engage in sexual intercourse with any other person and such act is accomplished (i) against the complaining witness's will, by force, threat or intimidation of or against the complaining witness or another person, or (ii) through the use of the complaining witness's mental incapacity or physical helplessness, or (iii) with a child under age thirteen as the victim, he or she shall be guilty of rape.
B. If any person has sexual intercourse with his or her spouse and such act is accomplished against the spouse's will by force, threat or intimidation of or against the spouse or another, he or she shall be guilty of rape.