Source : Webster's Revised Unabridged Dictionary (1913)

Malnutrition \Mal`nu*tri"tion\, n. [Mal- + nutrition.]
   (Physiol.)
   Faulty or imperfect nutrition.

Source : WordNet®

malnutrition
     n : a state of poor nutrition; can result from insufficient or
         excessive or unbalanced diet or from inability to absorb
         foods