Source : Webster's Revised Unabridged Dictionary (1913)

Tensor \Ten"sor\, n. [NL. See {Tension}.]
   1. (Anat.) A muscle that stretches a part, or renders it
      tense.

   2. (Geom.) The ratio of one vector to another in length, no
      regard being had to the direction of the two vectors; --
      so called because considered as a stretching factor in
      changing one vector into another. See {Versor}.

Source : WordNet®

tensor
     n 1: a generalization of the concept of a vector
     2: any of several muscles that cause an attached structure to
        become tense or firm