Millstone

['mɪlstəʊn] or ['mɪlston]

(noun.) one of a pair of heavy flat disk-shaped stones that are rotated against one another to grind the grain.

(noun.) any load that is difficult to carry.

Checked by Emma--From WordNet

(n.) One of two circular stones used for grinding grain or other substance.

Checker: Paulette

You see the millstone that he is about my neck. Charles Dickens. David Copperfield.
A porochial 'prentis, who is at present a dead-weight; a millstone, as I may say, round the porochial throat? Charles Dickens. Oliver Twist.
And really, there is no corn between the millstones any more. D. H. Lawrence. Women in Love .

Checker: Reginald