Source : Webster's Revised Unabridged Dictionary (1913)

Correlation \Cor`re*la"tion\ (-l?"sh?n), n. [LL. correlatio; L.
   cor- + relatio: cf. F. corr['e]lation. Cf. {Correlation}.]
   Reciprocal relation; corresponding similarity or parallelism
   of relation or law; capacity of being converted into, or of
   giving place to, one another, under certain conditions; as,
   the correlation of forces, or of zymotic diseases.

   {Correlation of energy}, the relation to one another of
      different forms of energy; -- usually having some
      reference to the principle of conservation of energy. See
      {Conservation of energy}, under {Conservation}.

   {Correlation of forces}, the relation between the forces
      which matter, endowed with various forms of energy, may
      exert.