The Collaborative International Dictionary of English v.0.48:

eutectic \eu*tec"tic\ ([=u]*t[e^]k"t[i^]k), a. [Gr. e'y`thktos
   easily melted; e'y^ well + th`kein to melt.] (Physics)
   Of maximum fusibility; -- said of an alloy or mixture which
   has the lowest melting point which it is possible to obtain
   by the combination of the given components.
   [Webster 1913 Suppl.]

The Collaborative International Dictionary of English v.0.48:

eutectic \eutectic\ ([=u]*t[e^]k"t[i^]k), n.
   a mixture of substances having a composition providing the
   minimum melting point ofr mixtures of those substances.
   Called also a eutectic mixture.

   Syn: eutectic mixture. [WordNet 1.5]

WordNet (r) 3.0 (2006):

eutectic
    n 1: a mixture of substances having a minimum melting point