From Longman Dictionary of Contemporary Englishpestlepes‧tle /ˈpesəl, ˈpestl/ noun [countable] 
DFUHCa short stick with a heavy round end, used for crushing things in a mortar (=a special bowl)
DFUHCa short stick with a heavy round end, used for crushing things in a mortar (=a special bowl)Examples from the Corpus
pestle• The handle is squared and flattened at the end which could mean that it was used as a pestle for grinding.• To keep the sound of pounding rice with a pestle to a minimum, Grandmother put a quilt under the mortar.• It has been suggested that such small cups and a pebble were an ancient form of mortar and pestle for grinding what?• Brayer a maker or seller of pestles.• Some hours later, out she went again, flying in her mortar and rowing it with the pestle.Origin pestle (1300-1400) Old French Latin pistillum; → PISTIL 