What is defined as the penetration, however slight, of the oral, anal, or vaginal opening with a penis?

The definition of rape specifically includes the penetration, no matter how slight, of the oral, anal, or vaginal openings with a penis. This is a legal definition that is central to determining whether an act constitutes rape under many jurisdictions' laws, including Idaho's. The focus on penetration emphasizes that sexual intercourse or acts that go beyond mere physical contact fall under this definition.

In contrast, other terms like sexual assault can encompass a broader range of sexual offenses, but they do not exclusively define the act of penetration required to classify an incident as rape. Forcible penetration may lead one to think of rape but lacks the precise legal language that highlights penetration with a penis specifically. Frottage, which refers to sexual rubbing or touching, does not apply here because it does not involve penetration at all. Therefore, the distinction made by the definition of rape is critical in interpreting and applying the law correctly in instances of sexual crimes.