Green’s Dictionary of Slang

1. a commercial traveller.

1884

G.R. Sims in Referee 28 Dec. n.p.: I loved the good old ‘com.’ I have spent many a pleasant even in commercial rooms with the shrewd men of the world who used to be bagmen, and who had strange tales of the road to tell.

2. a comedian.

1889		Music Hall & Theatre Rev. 1 June 5/1: A good example of a low com’ fallen into the public-matrimonial-and-frequent children line.
1890		Music Hall & Theatre Rev. 15 Feb. 12/1: Finlay and Rankin, nigger ‘coms’ [...] complete a good programme.

3. a commission (in a pecuniary sense).

1892		H. Nisbet Bushranger’s Sweetheart 75: I keep an eye on them for all that [...] else I might miss my com.
1893		P.H. Emerson Signor Lippo 87: Well, here’s your com., four bob.
1904		Sun. Times (Perth) 24 July 1/1: This Baptist blood-sucker wails that he has now ‘nothing but salary and com. to live on!’.
1947		Truth (Sydney) 5 Jan. 2/2: George was in such rare form that we thought he must have been handling the stable ‘com’.

4. a commission (in a non-pecuniary sense).

1905		Sydney Sportsman (Surrey Hills, NSW) 9 Aug. 5/4: A big traffic at once sprang up in the convict trade. Shipowners vied with each other in securing cargoes, and probably the maritime man who paid the best ‘com’ pulled off the deal.
1937–84		Partridge DSUE (1984) 240/2: from ca. 1860.

5. (orig. Aus., also comm) a communist.

1934		B. Traven Death Ship 169: Comms, you ass. I mean Bolshies. Communists, you bonehead.
1945		Worker (Brisbane) 19 Mar. 2/5: Having known Fred Parker, and having known a few ‘Coms,’ Fred fights too clean for the latter.
1950		(con. 1936–46) K.S. Prichard Winged Seeds (1984) 31: ’Course the coms were blamed.
1968		Aus. Jewish News (Melbourne) 20 Sept. 36/4: ‘[N]o comm is gonna push a dinkie-di Aussie around’.
1970		B. Oakley Salute to the Great McCarthy 113: An enemy group moves into the sun, the light breaking on rival slogans. [...] LOUSY COMS scores a hit on the head.
1976		N. Thornburg Cutter and Bone (2001) 236: Monk herself is a nigger-loving, com-symp, atheistic socialist with allergies.
1987		B. Chatwin Songlines 124: What did I tell you, Bert? A Pom and a Com!

6. (US Und., also comb) the combination of a safe.

1929		C.G. Givens ‘Chatter of Guns’ in Sat. Eve. Post 13 Apr.; list extracted in AS VI:2 (1930) 132: com, n. Combination of a safe.
1949		Monteleone Criminal Sl. (rev. edn) 55: com [...] comb The combination of a safe or vault.
1976		M. Braly False Starts 125: Day com is used when the manager of a store, fearing robbery, wants to give the impression his safe is locked.

7. (US campus) communication(s).

1997

Da Bomb Summer Supplement 4: Com (adj. & n.) Communication.

8. see combie n.