A flexible rodlike structure that forms the supporting axis of the body in the lowest chordates and lowest vertebrates and in embryos of higher vertebrates

Wiktionary Word definitions in Wiktionary
n. 1 A flexible rodlike structure that forms the main support of the body in the lowest chordates; a primitive spine 2 A similar structure found in the embryos of vertebrates from which the spine develops

Wikipedia Word definitions in Wikipedia
In animal anatomy , the notochord is a flexible rod made out of a material similar to cartilage . If a species has a notochord, it is, by definition, a chordate . The notochord lies along the anteroposterior ("head to tail") axis, is usually closer to the ...

WordNet Word definitions in WordNet
n. a flexible rodlike structure that forms the supporting axis of the body in the lowest chordates and lowest vertebrates and in embryos of higher vertebrates

Douglas Harper's Etymology Dictionary Word definitions in Douglas Harper's Etymology Dictionary
1848, coined in English by English anatomist Sir Richard Owen (1804-1892) from chord + comb. form of Greek noton "back," from PIE *not- "buttock, back" (cognates: Latin natis "buttock," sopurce of Italian, Spanish nalga , Old French nache "buttock, butt"). ...

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
Notochord \No"to*chord\, n. [Gr. nw^ton the back + E. chord.] (Anat.) An elastic cartilagelike rod which is developed beneath the medullary groove in the vertebrate embryo, and constitutes the primitive axial skeleton around which the centra of the vertebr[ae] ...