Tetrad

2 definitions found

From The Collaborative International Dictionary of English v.0.48 [gcide]:

  Tetrad \Tet"rad\, n. [L. tetras, -adis, Gr. ?, ?: cf. F.
     t['e]trade.]
     1. The number four; a collection of four things; a
        quaternion.
        [1913 Webster]
  


     2. (Chem.) A tetravalent or quadrivalent atom or radical; as,
        carbon is a tetrad.
        [1913 Webster] Tetradactyl

From WordNet (r) 2.0 [wn]:

  tetrad
       n : the cardinal number that is the sum of three and one [syn: {four},
            {4}, {IV}, {quatern}, {quaternion}, {quaternary}, {quaternity},
            {quartet}, {quadruplet}, {foursome}, {Little Joe}]