Proboscis \Pro*bos"cis\, n.; pl. Proboscides. [L. fr. Gr. ?; ? before + ? to feed, graze.]

1. (Zo["o]l.) A hollow organ or tube attached to the head, or connected with the mouth, of various animals, and generally used in taking food or drink; a snout; a trunk.

Note: The proboscis of an elephant is a flexible muscular elongation of the nose. The proboscis of insects is usually a chitinous tube formed by the modified maxill[ae], or by the labium. See Illusts. of Hemiptera and Lepidoptera.

2. (Zo["o]l.) By extension, applied to various tubelike mouth organs of the lower animals that can be everted or protruded.

Note: The proboscis of annelids and of mollusks is usually a portion of the pharynx that can be everted or protruded. That of nemerteans is a special long internal organ, not connected with the mouth, and not used in feeding, but capable of being protruded from a pore in the head. See Illust. in Appendix.

3. The nose. [Jocose]

Proboscis monkey. (Zo["o]l.) See Kahau.

Source: Webster's Revised Unabridged Dictionary (1913)