What's the meaning of the phrase 'Carnal Knowledge'?
Euphemism for sexual intercourse.
What's the origin of the phrase 'Carnal Knowledge'?
In 1532 Thomas More published a long treatise in which he laid out what he believed the English Church should be - The Confutacyon of Tyndales Answere. This contains the first known recorded use of 'carnal knowledge':
Yf they were clene from any late commyxcyon and carnall knowledge of theyr wyuys.
[If they were clean from any late commixion and carnal knowledge of their wives.]
In keeping with 'carnal knowledge; being an example of a euphemism, the word 'commixion', which is hardly ever now used, also means 'sexual intercourse'.