Source : Webster's Revised Unabridged Dictionary (1913)

Mastication \Mas`ti*ca"tion\, n. [L. masticatio: cf. F.
   mastication.]
   The act or operation of masticating; chewing, as of food.

         Mastication is a necessary preparation of solid
         aliment, without which there can be no good digestion.
                                                  --Arbuthnot.

Source : WordNet®

mastication
     n : biting and grinding food in your mouth so it becomes soft
         enough to swallow [syn: {chew}, {chewing}, {manduction}]