The term refers to leaving a party without bidding farewell to the host. The intent behind this behaviour was to leave without disturbing the host. This phrase has a corresponding French equivalent (to come), as the English and French cultures (in Europe) are intertwined.
Previously: A term (origin unknown) meant to convey the act of leisurely desertion from a military unit. To go away or do a thing without permission. See also List of common phrases based on stereotypes This is a list of common American and British Commonwealth words and phrases based on racial, ethnic, religious, regional or other stereotypes. ...
Leave can refer to paid or unpaid time off work, and is often covered by legislation, such as the United State's federal Family and Medical Leave Act of 1993.
Frenchleave refers to the leisurely desertion from a military unit.
If a person leaves the service without having used all his or her leave time, the unusued days are paid for at the soldier's regular rate of pay upon separation.
The allusion is to the French soldiers, who in their invasions take what they require, and never wait to ask permission of the owners or pay any price for what they take.
The French retort this courtesy by calling a creditor an Englishman (un Anglais), a term in vogue in the sixteenth century, and used by Clement Marot.
Leaving a party, house, or neighbourhood without bidding good-bye to anyone; to slip away unnoticed.