earthworm

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Any of various terrestrial annelid worms of the class Oligochaeta, especially those of the family Lumbricidae, that burrow into and help aerate and enrich soil.

from The Century Dictionary.

• noun The common name of the worms of the family Lumbricidæ (which see), and especially of the genus Lumbricus, of which there are several species, one of the best-known being L. terrestris.
• noun Figuratively, a mean, sordid wretch.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Zoöl.) Any worm of the genus Lumbricus and allied genera, found in damp soil. One of the largest and most abundant species in Europe and America is L. terrestris; many others are known; -- called also angleworm and dewworm.
• noun A mean, sordid person; a niggard.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A worm that lives in the ground; a worm of Lumbricidae family, or, more generally, of Lumbricina suborder.
• noun this sense?) (derogatory) A person, particularly one who grovels.
• noun figuratively Death.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun terrestrial worm that burrows into and helps aerate soil; often surfaces when the ground is cool or wet; used as bait by anglers