pay ‧ back /ˈpeɪbæk/ BrE AmE noun
1 . [countable] the money or advantage you gain from a business, project, or something you have done:
The immediate payback for them is publicity.
2 . [uncountable] American English informal when you do something to make someone suffer because of something they have done to harm you ⇨ revenge :
I guess it’s payback time.
3 . payback period
a) the period of time in which you will make a profit on an ↑ investment
b) the period of time over which you must pay back money you have borrowed