Yours, Etc.: Origins and Uses of 8 Sign-Offs
early 14c., from Old French congié "permission, leave of absence, dismissal, ceremonial leave-taking" (Modern French congé), from Latin commeatus "passage, going to and fro," hence "leave of absence," from commeare, from com- "with, together" (see com-) + meare "to go, pass" (see mutable). Probably lost 17c. and revived 19c. from Modern French.