Definition of Polychaeta in US English:


plural noun

  • A class of marine annelid worms which comprises the bristle worms.

    • ‘The phylum Annelida is traditionally divided into three classes: Oligochaeta, Hirudinida, and Polychaeta (marine annelids).’
    • ‘The term Polychaeta may no longer be valid because Polychaeta is likely a synonym for Annelida.’
    • ‘What is most striking with respect to character selection in Haszprunar's study, is that none of the characters that could indicate affinities with or within Polychaeta are coded in the data set (nor is Polychaeta divided into subtaxa).’
    • ‘In traditional classification schemes, the Annelida consists of the Polychaeta and the Clitellata (the latter including the Oligochaeta and Hirudinida).’
    • ‘These include some Foraminiferida, Hydrozoa and Scleractinia, Bryozoa, Brachiopoda, Pelecypoda, Polychaeta, and Cirripedia.’


Modern Latin (plural), from Greek polu- ‘many’ + khaitē ‘mane’ (taken to mean ‘bristle’).