Green’s Dictionary of Slang

outfit n.1

[‘to cross the plains, or go to the mountains, every one must get an outfit; and having outfitted, you become yourself an outfit’ J. F. Meline Two Thousand Miles on Horseback (1867)]

1. as a lit. or fig. piece of equipment.

(a) [mid-19C+] any object or device.

(b) [late 19C–1920s] (UK Und.) a burglar’s or safe-breaker’s equipment.

(c) [1940s–50s] (UK prison) whatever is needed for attempting a given escape.

(d) [1970s] (US Und.) a weapon.

2. of a collection of individuals.

(a) [mid-19C+] a travelling party or a party in charge of herds of cattle.

(b) [late 19C+] any group of people.

(c) [late 19C+] a criminal organization, a gang.

(d) [late 19C+] an organization, a business; a sports team.

(e) [20C+] a collection of inanimate objects or possessions.

(f) [1920s+] (US Und.) constr. as The Outfit, a specific criminal organization, usu. the US Mafia or Italian gangs in US prisons; also used as adj.

3. in drug uses.

(a) [late 19C+] equipment for the preparation and smoking of opium.

(b) [1920s+] (also bang outfit, fit) the equipment (needle, spoon, cotton etc) used for narcotic injection.

In phrases

whole outfit (n.)

[1910s+] the lot, everything.