NOTOCHORD
notochord
(noun) 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
Source: WordNet® 3.1
Etymology
Noun
notochord (plural notochords)
A flexible rodlike structure that forms the main support of the body in the lowest chordates; a primitive spine
A similar structure found in the embryos of vertebrates from which the spine develops
Source: Wiktionary
No"to*chord, n. Etym: [Gr. chord.] (Anat.)
Definition: 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 vertebræ and
the posterior part of the base of the skull are developed; the chorda
dorsalis. See Illust. of Ectoderm.
Source: Webster’s Unabridged Dictionary 1913 Edition