Definition of tagma in English:



  • (in the bodies of arthropods and some other segmented animals) a morphologically distinct region, typically comprising several adjoining segments, such as the head, thorax, and abdomen of insects.

    • ‘All hexapods have a body divided into three basic tagmata - head, thorax, and abdomen - and three pairs of thoracic legs.’
    • ‘The chelicerate body plan is characterized by two tagmata, the prosoma, including head structures, and the opisthosoma.’
    • ‘Ventral appendages suggest a different pattern of tagmosis, especially if tagmata are defined as zones of functional specialization, as is commonly the case when considering arthropod appendages.’
    • ‘As defined by Collins, Dinocarids are bilaterally symmetrical arthropods with a body divided into two principal tagmata, recalling the prosoma and opisthosoma of chelicerates, and a non-mineralised cuticle.’
    • ‘The distinct adult thorax and pygidia evident in some trilobites probably do deserve recognition as separate tagmata, but this may not be the case among all trilobites.’


Early 20th century: from Greek, literally ‘something arranged’, from tassein ‘set in order’.