bivalent

from WordNet (r) 3.0 (2006)

bivalent
    adj 1: having a valence of two or having two valences [syn:
           {bivalent}, {divalent}]
    2: used of homologous chromosomes associated in pairs in
       synapsis [syn: {bivalent}, {double}] [ant: {multivalent},
       {univalent}]

from The Collaborative International Dictionary of English v.0.48

Bivalent \Biv"a*lent\, a. [L. bis twice + valens, p. pr. See
   {Valence}.] (Chem.)
   Equivalent in combining or displacing power to two atoms of
   hydrogen; dyad.
   [1913 Webster]

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