(1):

(v. i.) To emit a grinding or craunching noise.

(2):

(v. i.) To grind or press with violence and noise.

(3):

(v. i.) To chew with force and noise; to craunch.

(4):

(v. t.) To crush with the teeth; to chew with a grinding noise; to craunch; as, to crunch a biscuit.