signoff (English) comes from English off, from Middle English of, from Old English of, from Old English æf, from Proto-Germanic *ab, from Proto-Indo-European apó.
signoff (English): The act or process of signing off; The process of...
Definitions
The act or process of signing off; The process of...
Ancestry of “signoff”, step by step
signoff traces back through two separate lines of ancestry.