The Collaborative International Dictionary of English v.0.48:
Milling \Mill"ing\, n.
The act or employment of grinding or passing through a mill;
the process of fulling; the process of making a raised or
intented edge upon coin, etc.; the process of dressing
surfaces of various shapes with rotary cutters. See Mill.
High milling, milling in which grain is reduced to flour by
a succession of crackings, or of slight and partial
crushings, alternately with sifting and sorting the
Low milling, milling in which the reduction is effected in
a single crushing or grinding.
Milling cutter, a fluted, sharp-edged rotary cutter for
dressing surfaces, as of metal, of various shapes.
Milling machine, a machine tool for dressing surfaces by
Milling tool, a roller with indented edge or surface, for
producing like indentations in metal by rolling pressure,
as in turning; a knurling tool; a milling cutter.