Hirudinea

The leeches, a class of worms (phylum Annelida) with flat, segmented bodies, a sucker at the posterior end, and often a smaller sucker at the anterior end; they are predatory on invertebrate tissues, or feed on blood and tissue exudates of vertebrates. [L. hirudo, leech]

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Hir·u·din·ea .hir-(y)ə-'din-ē-ə n pl a class of hermaphroditic aquatic, terrestrial, or parasitic annelid worms distinguished by a coelom nearly obliterated by connective tissue and reduced to a series of vascular sinuses, by modification of the hindmost segments into a sucking disk, and by the absence of parapodia and setae

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Hir·u·din·ea (hir″oo-dinґe-ə) the leeches, a class of the phylum Annelida; it includes the genera Haemadipsa, Haementeria, Haemopis, Hirudinaria, Hirudo, Limnatis, and Macrobdella. See also leech.