Noun
A mill for grinding grain; especially, a mill for grinding grists, or portions of grain brought by different customers; a custom mill.
Source: Webster's dictionaryAugustus and Peter Porter purchased this area and all of American Falls in 1805 from the New York state government, and enlarged the original canal to provide hydraulic power for their gristmill and tannery. Source: Internet
Madison may have sold or donated his gristmill in support of the ACS. Source: Internet