Definition of "earthworm" [earth•worm]

• 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. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "I have selected an unfortunate earthworm from the backyard and will be giving it to the planarian soon."
• "My Ph.D. thesis concerned the metabolic mechanism by which the end product of nitrogen metabolism in the earthworm is switched from ammonia to urea during starvation."
• "As far as a nine foot long earthworm, that isn't the scariest earthworm."