Underlip n. : The lower lip.

Example:
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Taxonomy
Merriam-Webster Online Dictionary, Dictionary, webster, lower lip, Word Games, Webster Online Dictionary with audio pronunciations, thesaurus, glossary, english, language, ESL, n-d, Unabridged Dictionary, Search Boxes, Open Dictionary, Pronunciation Symbols, Learner's Dictionary, Word Central.

Defination from the web:
underlip from the Merriam-Webster Online Dictionary with audio pronunciations, thesaurus, Word of the Day, and word games. ... Learn more about "underlip" Learn more about "underlip" and related topics at Britannica.com. Pronunciation Symbols. Share this entry: Link to this page: ...