Probably ultimately from the base of G3433 (through the idea of hardship); a {mill} that {is} (by implication) a grinder (millstone): - millstone.
Verse
Matrix
Mar 9:42And whosoever shall offend one of these little ones that believe in me, it is better for him that a millstoneG3457 were hanged about his neck, and he were cast into the sea.