Boyd’s Bible Dictionary:
(grind). A mortar and pestle; or, two stones, upper and nether, the former turned by hand (Job 41:24; Isa. 47:1-2; Matt. 24:41). Millstones not pawnable (Deut. 24:6).
Concise Bible Dictionary:
In the East these are usually small, every family having its own mill. A woman, or sometimes two sit at the mill, turning the upper stone, casting in the grain occasionally through a hole in it, Larger mills are also referred to, the stone being turned by an ass (Num. 11:8; Matt. 18:6; Mark 9:42; Rev. 18:21-22).
Strong’s Dictionary of Greek Words: