Source : Webster's Revised Unabridged Dictionary (1913)

Plant-eating \Plant"-eat`ing\, a.
   Eating, or subsisting on, plants; as, a plant-eating beetle.

Source : WordNet®

plant-eating
     adj : (of animals) feeding on plants [syn: {plant-eating(a)}, {phytophagic},
            {phytophagous}, {phytophilous}]