• synonyms


  1. any marine arthropod of the extinct class Trilobita, from the Paleozoic Era, having a flattened, oval body varying in length from 1 inch (2.5 cm) or less to 2 feet (61 cm).
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Origin of trilobite

1825–35; < New Latin Trilobites, equivalent to Greek trílob(os) three-lobed (see tri-, lobe) + -ītēs -ite1
Related formstri·lo·bit·ic [trahy-luh-bit-ik] /ˌtraɪ ləˈbɪt ɪk/, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for trilobite

Historical Examples

  • To the geologist man is just as much and just as little as a trilobite or a megatherium.

    Modern Skepticism

    C. J. Ellicott

  • I will also exchange minerals for stalagmites, and a trilobite for a stalactite.

  • The appendages are not known, but the test is in some ways like that of a trilobite.

  • Trilobite—trīlo-bīte, not trĭlo-bīte nor trŏllo-bīte, as it is often called.

  • One of the most abundant fossil animals in ancient rocks is called a trilobite.

British Dictionary definitions for trilobite


  1. any extinct marine arthropod of the group Trilobita, abundant in Palaeozoic times, having a segmented exoskeleton divided into three parts
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Derived Formstrilobitic (ˌtraɪləˈbɪtɪk), adjective

Word Origin

C19: from New Latin Trilobītēs, from Greek trilobos having three lobes; see tri-, lobe
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for trilobite


extinct marine arthropod, 1832, from Modern Latin Trilobites (Walch, 1771), from Greek tri- "three" (see three) + lobos "lobe" (see lobe); so called because its body is divided into three lobes.

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Online Etymology Dictionary, © 2010 Douglas Harper

trilobite in Science


  1. Any of numerous extinct and mostly small arthropods of the subphylum Trilobita that lived during the Paleozoic Era and are extremely common as fossils. Trilobites had a hard outer covering divided into three lengthwise and three widthwise sections. Their heads had two prominent compound eyes similar in structure to those of modern insects.
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The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.