1historical, rare A mill belonging to a feudal lord at which tenants are obliged to grind their grain, paying a proportion as tax. Compare customary mill .
2historical A mill which grinds grain for private or individual customers; opposed to merchant mill .
An independent mill which processes ore purchased from other mines.
Early 17th century; earliest use found in John Norden (c1547–1625), cartographer. From custom + mill.