Any element, atom, or radical, having a valence of five, or and that can be coupled with, substituted for, or in contrast to, five atoms of hydrogen or other monad.
Any grouping of five things.
the quantity five, in abstract: some five things considered collectively: since, the Pythagorean pentad: correlated with monad, dyad, triad, tetrad, etc.
Specifically A period of five successive years.
In chem., a feature one atom that would match five univalent atoms or radicals; a pentavalent element.
a time period of five times, introduced by Dove for usage in climatological study. The pentads begin January 1–5, and carry on in groups of five times each throughout the ordinary year. The twelfth pentad, from February 25-March 1, may be increased by one day, namely, February 29th, without disturbing the diary dates for the subsequent pentads.
the cardinal number that is the sum of four and one