I. intransitive verb
1. : to withdraw from an engagement or association
2. : to make a sign-off bid
partner signed off with four spades
3.
a. : to announce the end of a message, program, or broadcast and discontinue transmitting
b. : to end a speech or a conversation : fall silent
c. : to cease or withdraw from an activity : quit
II. intransitive verb
: to approve or acknowledge something by or as if by a signature — usually used with on
sign off on a memo