What Constitutes a Rape Act?

During Nels' excellent lecture, even as I was paying rapt attention, my mind kept wandering back to the idea of a definition of "rape" or a "rape act."  There are non-sexual definitions of rape (i.e. plunder), but I am not interested in those.  I think I might like my own definition of rape, to then petition all 50 states to adopt my over-arching denotation.  In trying to find what I consider to be rape, I looked up plenty of others' efforts.

"the unlawful compelling of a woman through physical force or duress to have sexual intercourse"  and "any act of sexual intercourse that is forced on a person" were the top two definitions on Dictionary.com.  The first obviously is gender-specific, and therefore nonsense, in my opinion.  The second is still not right - sexual intercourse cannot be the only act included in the idea of rape.

MedicineNet.com has an extremely long definition (being medically inclined, I suppose).  They include the possibility of any gender being a rapist and/or the victim, and also include the anus in their category of "rape-able" orifices.  They discuss the important distinctions between regular "rape" and statutory rape - and also give date-rape a loose definition.

I think that the best place to start my definition of rape would be at the word's origin.  Rape is derived from the Latin word "rapere" - which means "to seize."  I think this is totally applicable, and would say that perhaps rape should be defined as any sexual act that is forced - any person who "seizes" anyone else's body part (vagina, anus, mouth) for their own sexual enjoyment (or general perversion) should be considered a rapist.  Those boys who ejaculated all over a sleeping girl's face?  Rapists for sure, in my book.  

I am really interested in what other people think about this definition in progress.  Please leave a comment if you have a suggestion - and I may work more on my definition as the semester goes on...