millstone

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; {vi 31015-31016}Rev. 18:21-22).

Strong’s Dictionary of Greek Words:

Number:
3458 (find all occurrences in KJV Bible)
Greek:
μύλος
Transliteration:
mulos
Phonic:
moo’-los
Meaning:
probably ultimately from the base of 3433 (through the idea of hardship); a "mill", i.e. (by implication), a grinder (millstone)
KJV Usage:
millstone