UNIT n.
A single thing, as a magnitude or number, regarded as an undivided whole. Abstract unit, the unit of numeration; one taken in the abstract; the number represented by 1. The term is used in distinction from concrete, or determinate, unit, that is, a unit in which the kind of thing is expressed; a unit of measure or valu…
VERTEBRATA n.
ginous vertebræ, together with Amphioxus in which the backbone is represented by a simple undivided notochord. The Vertebrata always have a dorsal, or neural, cavity above the notochord or backbone, and a ventral, or visceral, cavity below it. The subdivisions or classes of Vertebrata are Mammalia, Aves, Reptilia, Amph…