'Gristmill' definitions:

Definition of 'gristmill'

(from WordNet)
noun
A mill for grinding grain (especially the customer's own grain)

Definition of 'Gristmill'

From: GCIDE
  • Gristmill \Grist"mill"\, n. A mill for grinding grain; especially, a mill for grinding grists, or portions of grain brought by different customers; a custom mill. [1913 Webster]