larva

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. The newly hatched, wingless, often wormlike form of many insects before metamorphosis.
2. n. The newly hatched, earliest stage of any of various animals that undergo metamorphosis, differing markedly in form and appearance from the adult.
3. n. Roman Mythology A malevolent spirit of the dead; a lemur.

Century Dictionary and Cyclopedia

1. n. In Roman mythology, a ghost; a specter; a shade: generally in the plural. Compare Lar, 1.
2. n. In zoology:
3. n. The early form of any animal which during its development is unlike its parent: thus the tadpole, the larva of the frog, is unlike the frog. It is most familiar as the name for an insect in the caterpillar or grub state; the first stage after the egg in the metamorphoses of insects, preceding the pupa or chrysalis; the first condition of an insect at its issuing from the egg, when it is usually in the form of a grub, caterpillar, or maggot. The term was applied by Linnæus in the sense that the larval stage of an insect masks or hides the true character or imago of the species. It was long only or chiefly an entomological term, but is now commonly extended to other animals than insects, and especially other arthropods which undergo transformation. See pupa, imago, and cuts under Asteroidea, Cirripedia, Diptera, glass-crab, hag-moth, Holothuroidea, and house-fly.
4. n. A genus of mollusks.
5. n. A genus of birds: same as Alca.

Wiktionary

1. n. An early stage of growth for some insects and amphibians, in which after hatching from their egg, insects are wingless and resemble a caterpillar or grub, and amphibians lack limbs and ressemble fish.
2. n. An animal in the aforementioned stage.
3. n. A form of recently born or hatched animal that is quite different from its adult stage.

GNU Webster's 1913

1. n. (Zoöl.) Any young insect from the time that it hatches from the egg until it becomes a pupa, or chrysalis. During this time it usually molts several times, and may change its form or color each time. The larvæ of many insects are much like the adults in form and habits, but have no trace of wings, the rudimentary wings appearing only in the pupa stage. In other groups of insects the larvæ are totally unlike the parents in structure and habits, and are called caterpillars, grubs, maggots, etc.
2. n. (Zoöl.) The early, immature form of any animal when more or less of a metamorphosis takes place, before the assumption of the mature shape.

WordNet 3.0

1. n. the immature free-living form of most invertebrates and amphibians and fish which at hatching from the egg is fundamentally unlike its parent and must metamorphose