pop ‧ per /ˈpɒpə $ ˈpɑːpər/ BrE AmE noun
1 . [countable] British English informal a small metal thing that is used to fasten clothes, which works when you press its two parts together SYN snap American English
2 . poppers [plural] informal an illegal drug in the form of a liquid, which people take for pleasure by breathing it in