GNU Collaborative International Dictionary of English

last match results

Found 2 definitions

1.       
   Pentad (?), n. [Gr. πεντάς πεντάδος, a body of five, fr. πέντε 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]
   
   
         
       

2.       
   Pentad, a. (Chem.) Having the valence of a pentad.
   
   [1913 Webster]