1
general::
Phrase(s): switch someone or something off
to cause someone or something to be quiet or stop doing something. • I got tired of listening to her, so I punched the button and switched her off. • I switched off the television set., Phrase(s): switch off
1. Lit. [for something] to turn itself off. • At midnight, all the lights switched off automatically. • The television switched off after I went to sleep. 2. Fig. [for someone] to stop paying attention; to become oblivious to everything. • I got tired of listening and switched off. • You could see that the audience was switching off.
McGrawhill's American Idioms And Phrasal Verbs
2
general::
Stop paying attention, lose interest, as in Whenever he starts in on economics, I switch off automatically. This metaphoric expression transfers turning off a light switch or similar device to diverting one's attention. [c. 1860] Also see SWITCH ON.
American Heritage Idioms