[n] the cardinal number that is the sum of four and one
5, cinque, fin, five, fivesome, Little Phoebe, Phoebe, quint, quintet, quintuplet, V
\Pen"tad\, n. [Gr. ?, ?, a body of five, fr. ? five.] (Chem.) Any element, atom, or radical, having a valence of five, or which can be combined with, substituted for, or compared with, five atoms of hydrogen or other monad; as, nitrogen is a pentad in the ammonium compounds.
\Pen"tad\, a. (Chem.) Having the valence of a pentad.