PENTAD
five, cinque, quint, quintet, fivesome, quintuplet, pentad, fin, Phoebe, Little Phoebe
(noun) the cardinal number that is the sum of four and one
Source: WordNet® 3.1
Etymology
Noun
pentad (plural pentads)
A group or series of five things.
A mean average value of temperature, etc, taken every five days.
(chemistry) 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.
Synonyms
• (group of five): fivesome; see also quintet
Coordinate terms
• monad · duad, dyad · triad · tetrad · pentad · hexad · heptad · octad · ennead, nonad · decad, decade · hendecad · dodecad, duodecade
Anagrams
• panted, pedant
Source: Wiktionary
Pen"tad, n. Etym: [Gr. (Chem.)
Definition: 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.)
Definition: Having the valence of a pentad.
Source: Webster’s Unabridged Dictionary 1913 Edition