Source : Webster's Revised Unabridged Dictionary (1913)

Contraindication \Con"tra*in`di*ca"tion\, n. (med.)
   An indication or symptom which forbids the method of
   treatment usual in such cases.

Source : WordNet®

contraindication
     n : (medicine) a reason that makes it inadvisable to prescribe a
         particular drug or employ a particular procedure or
         treatment [ant: {indication}]