Source : Webster's Revised Unabridged Dictionary (1913)

   {Accumulation}, {Conservation}, {Correlation}, & {Degradation
   of energy}, etc. (Physics) See under {Accumulation},
      {Conservation}, {Correlation}, etc.

   Syn: Force; power; potency; vigor; strength; spirit;
        efficiency; resolution.

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.

Source : WordNet®

correlation
     n 1: a reciprocal relation between two or more things [syn: {correlativity}]
     2: a statistic representing how closely two variables co-vary;
        it can vary from -1 (perfect negative correlation) through
        0 (no correlation) to +1 (perfect positive correlation);
        "what is the correlation between those two variables?"
        [syn: {correlation coefficient}, {coefficient of
        correlation}]
     3: a statistical relation between two or more variables such
        that systematic changes in the value of one variable are
        accompanied by systematic changes in the other [syn: {correlational
        statistics}]