Definition of Trilobita in US English:



  • With plural (or occasionally singular) concord: a large group of extinct multi-legged arthropods that occurred abundantly in Palaeozoic seas, typically having a flattened oval body with a solid head section (cephalon) with antennae and compound eyes, a flexible segmented thorax, and a solid tail section (pygidium), all of which are divided into three longitudinal lobes. Also treated as plural: animals of this group (collectively or individually); trilobites.


Mid 19th century; earliest use found in Reports of the British Association for the Advancement of Science. From scientific Latin Trilobita from German Trilobit + -a.