Pronunciation: (mouth'fool"),[key] —n., —pl.-fuls. 1. the amount a mouth can hold.
2. the amount taken into the mouth at one time.
3. a small quantity.
4. Informal.a spoken remark of great truth, relevance, effectiveness, etc.: You said a mouthful! 5. a long word or group of words, esp. one that is hard to pronounce.