Green’s Dictionary of Slang

cocum n.

also cokum, kokum
[Heb. and thence Yid. kochum, wisdom]

1. advantage, luck, resource.

[UK]Hotten Dict. of Modern Sl. etc.
[UK](con. 1840s–50s) H. Mayhew London Labour and London Poor I 259/2: That’s my cokum (advantage).
[UK]Hotten Sl. Dict.

2. knowledge, cunning; thus do the cocum, fight cocum, being cunning, artful, usu. in illegal contexts.

[UK]Era (London) 7 Sept. 11/4: The youth who is surnamed Adam, in consequence of the depth of his cocum.
Man of Pleasure’s Illus. Pocket-book n.p.: [I]f you do the coakham, and tumble to the slum, you may fake the duck in rumbo style.
[UK]‘Ducange Anglicus’ Vulgar Tongue 9: cocum [...] To fight cocum, to be wary.
[UK]Hotten Dict. of Modern Sl. etc. (2nd edn) 119: ‘To fight cocum,’ to be wily and cautious.
[Aus] gloss. in Occurence Book of York River Lockup in Seal (1999) 36: I have got the yacks so do not come to fight cocum.
[UK]Sl. Dict. 124: Cocum shrewdness, ability, luck; “Jack’s got COCUM, he’s safe to get on, he is,” ― viz., he starts under favourable circumstances; “to fight COCUM” is to be wily and cautious.
[UK]C. Hindley Life and Adventures of a Cheap Jack 37: It was necessary to use a little judgment, and instead of attempting to fight them it would be far better to ‘fight cocum’.
[Aus]Queenslander (Brisbane) 10 Mar. 21/1: We have the ‘cokum’ to appreciate the selectors’ usefulness.
[UK]Newcastle Courant 9 Sept. 6/5: With the aid of his friends and his own ‘cocum,’ he made his peace with his mistress.
[Aus]Sydney Sportsman (Surry Hills, NSW) 16 Nov. 1/1: [T]he success he attains is solely attributable to the bit of ‘kokum’.
[Aus]Williamstown Chron. (Vic.) 26 Nov. 2/3: Mr Badman showed some ‘kokum’ when he decided to leave the Stardrift horse in the care of Bob.

3. sense.

[UK]Leaves from Diary of Celebrated Burglar 6/1: Very few honest people entered this house, as it was a well known resort of the Leeds ‘cross’ [...] and that it was bad ‘cocum’ to go there.
Cumberland Mercury (NSW) 8 Oct. 6/6: Nobbs showed his usual ‘kokum’ in leaving the chair before the ‘fun’ began on Saturday.
[Aus]Sydney Sportsman (Surry Hills, NSW) 28 Nov. 1/1: It proves them as not having sufficient cokum not to know when they are making first-class omadhauns of themselves.
[UK]Guardian 6 Mar. [Internet] Common cokum [...] meant Tessa Jowell telling her husband long ago that ‘I have to comply with these ministerial code provisions – is there anything I need to know?’.

4. (also kokum) deceit, entrapment; thus give someone kokum, to deceive.

[Aus]Portland Guardian 27 Oct. 2/7: Is the old fellow going to surprise us, and is it all ‘cokum’ about his leg? Spare my days, he gallops — yes, gallops.
[Aus]Stephens & O’Brien Materials for a Dict. of Aus. Sl. [unpub. ms.] 92: KOKUM-KID-TAFFY: leading or coaxing on, giving him kokum.

5. (S.Afr. Und., also chochem) a thief, usu. an intelligent one.

[SA]L.F. Freed Crime in S. Afr. 106: A ‘chochem’ is a thief or crook who considers the risks involved in a robbery.

In phrases

play cocum (v.) (also play cokum)

to act in an artful, cunning manner; to deceive.

[UK]J. Archbold Magistrate’s Assistant (3rd edn) 445: play cocum To be cunning, wary, or sly.
[UK]Referee 26 Apr. 1/2: The best show [...] unless a lot of the pulling-up division were playing cokum – was that of Ptolemy [F&H].