lugworm

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

• noun Any of various burrowing marine annelid worms of the genus Arenicola, especially A. marina, often used as fishing bait.

from The Century Dictionary.

• noun An annelid of the family Arenicolidæ, inhabiting the sea-shore.

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

• noun (Zoöl.) A large marine annelid (Arenicola marina) having a row of tufted gills along each side of the back. It is found burrowing in sandy beaches, both in America and Europe, and is used for bait by European fishermen. Called also lobworm, and baitworm.

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

• noun A large marine annelid worm of the species Arenicola marina, whose coiled castings can often be seen on beaches at low tide.

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

• noun marine worms having a row of tufted gills along each side of the back; often used for fishing bait