B2 [ C ] either of the two areas of firm pink flesh inside the mouth that cover the bones into which the teeth are fixed:

[ U ] a sticky substance that comes from the stems of some trees and plants

[ U ] a type of glue used for sticking together pieces of paper

[ U ] chewing gum or bubble gum (= a soft sweet that you crush with your teeth but do not swallow)

[ C ] UK used in the names of some chewy sweets with fruit flavours:

If you gum one piece of paper to another, you stick them together using glue: