Carnal knowledge is the sexual intercourse between a man and a woman, in which the man`s penis enters the woman`s vagina. This is a necessary legal element of rape, child abuse or consensual sexual relations with a woman under the age of consent (“legal rape”). State laws vary, but the age of consent is usually between 14 and 18. Here is an example of a state law that includes carnal knowledge: “Carnal knowledge.” Merriam-Webster.com Legal Dictionary, Merriam-Webster, www.merriam-webster.com/legal/carnal%20knowledge. Accessed January 14, 2022. Note: Carnal knowledge is sometimes an element of the legal definition of rape and a separate crime. 2.