an archaic or legal euphemism for sexual intercourse. The term derives from the Biblical usage of the verb know/knew, as in the King James and other versions, a euphemism for sexual conduct.
In criminal law, the phrase has had different meanings at different times and in different jurisdictions. While commonly a mere euphemism for sexual intercourse (not necessarily unlawful), different jurisdictions have defined carnal knowledge as a specific sex act such as contact between a penis and vagina, some laws elaborating this to include even “slight penile penetration of female sex organs”. The definition sometimes includes a set of sex acts that include sodomy and/or oral sex, while some statutes specifically exclude such acts.
Carnal knowledge has also sometimes meant sexual intercourse outside of marriage, and sometimes refers to sex with someone under the age of consent. The phrase is often found in this sense in modern legal usage, being equivalent to statutory rape in some jurisdictions, as the term “rape” implies lack of consent.