1
general::
Pay to get rid of a claim or opposition, or to avoid prosecution, as in He was caught trying to buy off the opposing candidate. [First half of 1600s]
American Heritage Idioms
2
general::
Phrase(s): buy someone off
to bribe someone to ignore what one is doing wrong. • Do you think you can buy her off ? • The mobster tried to buy off the jury.
McGrawhill's American Idioms And Phrasal Verbs