lugworm

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Any of various segmented, burrowing marine worms of the genus Arenicola, especially A. marina, often used as fishing bait. Also called lobworm.

Century Dictionary and Cyclopedia

1. n. An annelid of the family Arenicolidæ, inhabiting the sea-shore. A common species is Arenicola piscatorum, a large worm, 8 or 10 inches long, much used for bait. It belongs to a different order from the earthworm proper, though its habits are similar. It crawls through sandy and muddy soil, eating its way as it goes, and leaving in its wake coiled casts of the soil thus passed through its body. The head is large, eyeless and jawless, with a proboscis; the gills are thirteen pairs of gaily colored tufts, and the rings of the body are furnished with bristles like those of other chætopod worms. Also called lobworm and lugbait.

Wiktionary

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

GNU Webster's 1913

1. n. (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.

WordNet 3.0

1. n. marine worms having a row of tufted gills along each side of the back; often used for fishing bait