Chordata

The phylum that includes the vertebrates, defined by possession of: 1) a single dorsal nerve cord (the brain and spinal cord of mammals); 2) a cartilaginous rod, the notochord, which forms dorsal to the primitive gut in the early embryo, and is surrounded and replaced by the vertebral column in the subphylum vertebrata; 3) by presence at some stage in development of gill slits in the pharynx or throat. [L. chorda, fr. G. chorde, a string]

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Chor·da·ta kȯr-'dät-ə, -'dāt-ə n pl a phylum comprising animals having at least at some stage of development a more or less well-developed notochord, a dorsally situated central nervous system, and gill clefts in the walls of the pharynx and including the vertebrates, lancelets, and tunicates

chor·date 'kȯ(ə)r-.dāt, 'kȯrd-ət n or adj

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Chor·da·ta (kor-daґtə) [L. chordatus having a cord] a phylum of the animal kingdom comprising all animals that have a notochord during some stage of their development. It includes the subphyla Cephalochordata, Urochordata, and Vertebrata.