1. [mid-16C–mid-19C] the vagina [a play on SE grind/grind v. (1)].
2. in (UK Und.) use [SE mill, covering a variety of engines and tools].
(a) [17C] a housebreaker.
(b) [late 17C–early 18C] housebreaking.
(c) [17C–mid-19C] a chisel.
3. [early 19C–1930s] a fist-fight [mill v.1 (3)].
(a) a prize-fight.
(b) a fight, a brawl. sometimes a battle.
(c) a blow, a punch.
4. in sense of going or passing or putting through the mill.
(a) [mid-19C] (UK Und.) the Insolvent Debtors’ Court.
(b) [late 19C+] any institution that acts to process its affairs by rote, rather than deal with them on their individual merits.
(c) [1950s+] (US drugs) anywhere that pure narcotics (e.g. heroin, crack cocaine), purchased in bulk, is diluted and packaged for street sales.
5. in context of imprisonment.
(a) [mid–late 19C] a treadmill.
(b) [mid-19C–1940s] a prison; thus attrib (see cite 1838).
(c) [late 19C–1940s] a military prison or guardhouse.
6. [1900s] (US) a bar.
7. as a machine.
(a) [1910s+] (US) a typewriter [it ‘grinds out’ the words].
(b) [1910s+] (US) an engine of an aircraft or ‘souped up’ car; thus turn the mill, start the engine [note WWI Fr. sl. moulin à café, ‘coffee-grinder’, i.e. a machine gun, operated by a crank handle].
8. [1930s] (US) by metonymy from sense 1 above, a woman.
see separate entries.
[mid-19C] (UK Und.) a spell of hard labour in prison.
[mid-18C] a lodging house.
[late 17C–early 19C] breaking and entering for the purpose of robbery; thus mill-layer, a housebreaker.
[mid-19C] the testicles.
engaged in sexual intercourse.
[mid-19C] (W.I.) to walk on the prison treadmill.
see wigs on the green under wig n.2
SE in slang uses
[late 17C–19C] a (woman’s) tongue.
see under soak v.1