any unsegmented worm of the group Nemathelminthes, including the nematodes, nematomorphs, and acanthocephalans
nemathelminth in American English
(ˌnɛməˈθɛlˌmɪnθ)
noun
in some former classifications, any of a large phylum (Nemathelminthes) of round, unsegmented worms, many of which are parasitic, as the hookworm, gordian worm, etc.