/mil"stohn'/ , n.
1. either of a pair of circular stones between which grain or another substance is ground, as in a mill.
2. anything that grinds or crushes.
3. any heavy mental or emotional burden (often used in the phrase a millstone around one's neck ).
[ bef. 1050; ME milneston, OE mylenstan. See MILL 1 , STONE ]