Source : Webster's Revised Unabridged Dictionary (1913)

Malthusian \Mal*thu"sian\, a.
   Of or pertaining to the political economist, the Rev. T. R.
   Malthus, or conforming to his views; as, Malthusian theories.

   Note: Malthus held that population tends to increase faster
         than its means of subsistence can be made to do, and
         hence that the lower classes must necessarily suffer
         more or less from lack of food, unless an increase of
         population be checked by prudential restraint or
         otherwise.

Source : WordNet®

Malthusian
     adj : of or relating to Thomas Malthus or to Malthusianism;
           "Malthusian theories"

Malthusian
     n : a believer in Malthusian theory