ligula

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A strap-shaped or tonguelike structure, especially a mouth part in certain insects.

Century Dictionary and Cyclopedia

1. n. In botany, same as ligule.
2. n. In entomology: A fleshy, membranaceous, or horny anterior part of the labium, attached to the inner surface of the mentum, by which it is sometimes entirely concealed; the terminal or distal one of the three component parts of the labium. In the Hymenoptera it is developed into a long tongue-like organ, split into three parts, of which the outer two are called the paraglossæ and the intermediate one the glossa or lingua. (See cut under Hymenoptera.) Sometimes the term ligula is applied to the united palpigers or palpus-bearing lobes of the labium, which cover and conceal the true ligula. In the Coleoptera the ligula is properly the central division of the labium, between the paraglossæ; but, as the latter are often wanting, the term ligula has come to be used synonymously with labium, where the term labium is used as applying only to the anterior division, excluding mentum and submentum. See cut under mouth-parts.
3. n. A process on the elytra of certain beetles. See elytral.—
4. n. In anatomy, a band of white nervous substance bordering the membranous covering of the posterior part of the fourth ventricle of the brain on each side, and extending from the clava to the striæ acusticæ, where it winds around the restiform bodies. Also called tænia ventriculi quarti, ala pontis, and ponticulus.
5. n. [capitalized] A genus of simple cestoid worms, type of family Ligulidæ, having an unsegmented elongated body with two lateral depressions at the head end, and numerous sets of sexual organs in longitudinal series opening on the median line of the body. These endoparasites inhabit fishes and amphibians, and acquire their matured character in water-birds.
6. n. [capitalized] A genus of mollusks.

Wiktionary

1. n. A strap or strap-shaped object, especially such a development in plants or insects

GNU Webster's 1913

1. n. (Bot.) See ligule.
2. n. The central process, or front edge, of the labium of insects. It sometimes serves as a tongue or proboscis, as in bees.
3. n. A tongue-shaped lobe of the parapodia of annelids. See Parapodium.