A beak or bill was the protruding mouth of a bird.
In 2374, while recording her personal log, Seven of Nine described a bird she saw in her hallucinations as having "a powerful triangular beak". (VOY: "The Raven")
In 2380, one of the Osler's passengers heading to The Farm had a duck bill. (LD: "Much Ado About Boimler")
Disgusted with his simpering behavior, Peanut Hamper told Rawda to grow a beak. (LD: "A Mathematically Perfect Redemption")