pes·tle 
(pĕsəl, pĕstəl)
(pĕsəl, pĕstəl)n.
1. A club-shaped, handheld tool for grinding or mashing substances in a mortar.
2. A large bar moved vertically to stamp or pound, as in a press or mill.
v. pes·tled, pes·tling, pes·tles
v.tr.
To pound, grind, or mash with or as if with a pestle.
v.intr.
To use a pestle.
[Middle English pestel, from Old French, from Latin pistillum.]
pestlepestle (foreground) and mortar (background)