mouth ‧ ful /ˈmaʊθfʊl/ BrE AmE noun [countable]
1 . an amount of food or drink that you put into your mouth at one time:
Michael told his story between mouthfuls.
mouthful of
Betty drank a mouthful of beer.
He took a mouthful of his pudding.
2 . (a bit of) a mouthful informal a long word or phrase that is difficult to say:
Her real name is a bit of a mouthful, so we just call her Dee.
3 . give somebody a mouthful informal especially British English to speak angrily to someone, often swearing at them
4 . say a mouthful American English informal to say a lot of true and important things about something in a few words