Source : Webster's Revised Unabridged Dictionary (1913)

Symmetric \Sym*met"ric\, a.
   Symmetrical.

Source : WordNet®

symmetric
     adj : having similarity in size, shape, and relative position of
           corresponding parts [syn: {symmetrical}] [ant: {asymmetrical}]

Source : Free On-Line Dictionary of Computing

symmetric
     
         1. A {relation} R is symmetric if, for all x and
        y,
     
        	x R y  =>  y R x
     
        If it is also {antisymmetric} (x R y & y R x => x == y) then
        x R y => x == y, i.e. no two different elements are related.
     
        2. In {linear algebra}, a member of the {tensor product} of a
        {vector space} with itself one or more times, is symmetric if
        it is a {fixed point} of all of the {linear isomorphisms} of
        the tensor product generated by {permutations} of the ordering
        of the copies of the vector space as factors.  It is said to
        be antisymmetric precisely if the action of any of these
        linear maps, on the given tensor, is equivalent to
        multiplication by the sign of the permutation in question.
     
        (1996-09-22)