(1):

(n.) An implement for pounding and breaking or braying substances in a mortar.

(2):

(n.) A constable's or bailiff's staff; - so called from its shape.

(3):

(n.) The leg and leg bone of an animal, especially of a pig; as, a pestle of pork.

(4):

(v. t. & i.) To pound, pulverize, bray, or mix with a pestle, or as with a pestle; to use a pestle.