n. [ Gr. penta`s penta`dos, a body of five, fr. pe`nte 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. [ 1913 Webster ]

2. Any grouping of five things. [ PJC ]

a. (Chem.) Having the valence of a pentad. [ 1913 Webster ]

{ } a. [ Gr. pentada`ktylos with five fingers or toes. See Penta-, and Dactyl. ] 1. (Anat.) Having five digits to the hand or foot. [ 1913 Webster ]

2. Having five appendages resembling fingers or toes. [ 1913 Webster ]

a. [ Pentadactyl + -oid. ] (Anat.) Having the form of, or a structure modified from, a pentadactyl limb. [ 1913 Webster ]

n. [ Penta- + Gr. de`ka ten. ] (Chem.) A hydrocarbon of the paraffin series, (C15H32) found in petroleum, tar oil, etc., and obtained as a colorless liquid; -- so called from the fifteen carbon atoms in the molecule. [ 1913 Webster ]

a. [ Penta- + decatoic. ] (Chem.) Of, pertaining to, or derived from, pentadecane, or designating an acid related to it. [ 1913 Webster ]

a. [ Penta- + decylic. ] (Chem.) Same as Quindecylic. [ 1913 Webster ]

a. [ Penta- + Gr. 'adelfo`s brother. ] (Bot.) Having the stamens arranged in five clusters, those of each cluster having their filaments more or less united, as the flowers of the linden. [ 1913 Webster ]