ovipositor

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A tubular structure, usually concealed but sometimes extending outside the abdomen, with which many female insects deposit eggs.
2. n. A similar organ of certain fishes.

Century Dictionary and Cyclopedia

1. n. The ovipositing organ with which many (especially hymenopterous, orthopterous, coleopterous, and dipterous) insects are provided, and by means of which they place their eggs in a position suitable for development. It forms the end of the abdomen, several of the rings or somites of which are specially modified for this purpose. It normally or usually consists of three pairs of rhabdites, the outer two pairs of which incase or sheathe the inner pair, and form an extensile tube, of very variable size and shape in different insects. It is sometimes longer than the body of the insect. In the terebrant hymenopters the ovipositor forms a saw or an auger (serra or terebra). In the aculeate hymenopters, as bees and wasps, the ovipositor is the sting or aculeus. In orthopters it is often conspicuous, as seen in the cut. Also called oviscapt. See also cuts under canker-worm and Cecidomyia.

Wiktionary

1. n. zoology A tubular protruding organ for laying eggs.

GNU Webster's 1913

1. n. (Zoöl.) The organ with which many insects and some other animals deposit their eggs. Some ichneumon files have a long ovipositor fitted to pierce the eggs or larvæ of other insects, in order to lay their own eggs within the same.

WordNet 3.0

1. n. egg-laying tubular structure at the end of the abdomen in many female insects and some fishes