1
general::
Phrase(s): sign off
1. Lit. [for a broadcaster] to announce the end of programming for the day; [for an amateur radio operator] to announce the end of a transmission. • Wally signed off and turned the transmitter off. • Channel 43 failed to sign off at the scheduled time last night. 2. Fig. to quit doing what one has been doing and leave, go to bed, quit trying to do something, etc. • I have to sign off and get to bed. See you all. • When you finally sign off tonight, please turn out all the lights.
McGrawhill's American Idioms And Phrasal Verbs
2
general::
1. Announce the end of a communication, especially a broadcast. For example, There's no one there now; the station has signed off for the night. [c. 1920] 2. Stop talking, become silent, as in Every time the subject of marriage came up, Harold signed off. [Colloquial; mid-1900s] 3. Express approval formally or conclusively, as in The President got the majority leader to sign off on the tax proposal. This usage is colloquial.
American Heritage Idioms