'Cankerworm' definitions:

Definition of 'cankerworm'

noun

Green caterpillar of a geometrid moth; pest of various fruit and shade trees

From: GCIDE

Cankerworm \Can"ker*worm`\, n. (Zool.) The larva of two species of geometrid moths which are very injurious to fruit and shade trees by eating, and often entirely destroying, the foliage. Other similar larv[ae] are also called cankerworms. [1913 Webster]
Note: The autumnal species (Anisopteryx pometaria) becomes adult late in autumn (after frosts) and in winter. The spring species (Anisopteryx vernata) remains in the ground through the winter, and matures in early spring. Both have winged males and wingless females. The larv[ae] are similar in appearance and habits, and belong to the family of measuring worms or spanworms. These larv[ae] hatch from the eggs when the leaves begin to expand in spring. [1913 Webster]

From: GCIDE

Dropworm \Drop"worm`\ (dr[o^]p"w[^u]rm`), n. (Zool.) The larva of any geometrid moth, which drops from trees by means of a thread of silk, as the cankerworm or inchworm. See inchworm and geometrid. [1913 Webster]

From: GCIDE

Caterpillar \Cat"er*pil`lar\, n. [OE. catyrpel, corrupted fr. OF. chatepelouse, or cate pelue, fr. chate, F. chatte, she-cat, fem. of chat, L. catus + L. pilosus hairy, or F. pelu hairy, fr. L. pilus hair. See Cat, and Pile hair.]
1. (Zool.) The larval state of a butterfly or any lepidopterous insect; sometimes, but less commonly, the larval state of other insects, as the sawflies, which are also called false caterpillars. The true caterpillars have three pairs of true legs, and several pairs of abdominal fleshy legs (prolegs) armed with hooks. Some are hairy, others naked. They usually feed on leaves, fruit, and succulent vegetables, being often very destructive, Many of them are popularly called worms, as the cutworm, cankerworm, army worm, cotton worm, silkworm. [1913 Webster]
2. (Bot.) A plant of the genus Scorpiurus, with pods resembling caterpillars. [1913 Webster]
Caterpillar catcher, or Caterpillar eater (Zool.), a bird belonging to the family of Shrikes, which feeds on caterpillars. The name is also given to several other birds.
Caterpillar hunter (Zool.), any species of beetles of the genus Callosoma and other allied genera of the family Carabid[ae] which feed habitually upon caterpillars. [1913 Webster]

Cankerworm (Heb. yelek), "the licking locust," which licks up the grass of the field; probably the locust at a certain stage of its growth, just as it emerges from the caterpillar state (Joel 1:4; 2:25). The word is rendered "caterpillar" in Ps. 105:34; Jer. 51:14, 17 (but R.V. "canker-worm"). "It spoileth and fleeth away" (Nah. 3:16), or as some read the passage, "The cankerworm putteth off [i.e., the envelope of its wings], and fleeth away."