deadwood, n. — Green’s Dictionary of Slang

deadwood n.

[pun]

1. (US) a coffin.

1846

Durivage & Burnham Stray Subjects (1848) 71: I foller not the trade / I did afore they made my bed / With mattock and with spade, / And I was took to my last home, / And in the dead wood laid.

2. one who is caught committing a crime.

1936		D. Maurer ‘Argot of the Und. Narcotic Addict’ Pt 1 in AS XI:2 120/2: deadwood. The thing an addict fears most: to be trapped by an agent posing as a panic man. Many addicts find it very difficult to resist a plea for dope from another addict who is desperate.
1949		Monteleone Criminal Sl. (rev. edn).
1992		Bentley & Corbett Prison Sl. 92: Dead Wood [...] A person who is caught redhanded committing a crime.

3. a useless individual.

2013

T. Black ‘I Want Candy’ in Killing Time in Las Vegas [ebook] Delago was riding me: [...] ‘Get that fucking deadwood away from the dumpsters.’He was talking about the winos.

SE in slang uses

In phrases

have the deadwood on (v.) (also get the deadwood on, get/have/hold the wood on, have the deady on) [logging use, where a skilled axeman would cut a tree in such a way that he spared himself work by ensuring that any dead wood broke off by itself when the tree fell; alternate ety. suggests the shooting in the back of Marshall James Butler ‘Wild Bill’ Hickok in the town of Deadwood, South Dakota on 2 August 1876; ? or in ten-pin bowling, if a single pin is left lying in front of those that have not been knocked down, hitting that ‘dead wood’ will knock it into the others, successfully knocking them all down]

(Aus./US) usu. of individuals, to have at a disadvantage, to control, esp. through the possession of incriminating information; occas. of inanimate object, see cite 1882 (2).

1851		L. Clappe in Shirley Letters (1949) 52: If they ask a man an embarrassing question, or in any way have placed him in an equivocal position, they will triumphantly declare that they have ‘got the dead-wood on him’.
1865		M. MacFie Vancouver Island and British Columbia 415: If one have the best of a bargain, he is said to have got ‘the dead wood’ on the other party in the transaction.
1872		G.P. Burnham Memoirs of the US Secret Service 99: ‘You’ve got the “dead wood” on me, Colonel,’ said Bill despondingly. ‘I know it, and I knock under.’.
1882		Nat. Police Gaz. (NY) 4 Mar. 7/4: Mary Welles, who was supposed to have the ‘dead wood,’ emotionally speaking, on a lucky young miner named Ben Jial [...] inasmuch as she had shaken all the boys for him.
1882		Sweet & Knox Sketches from ‘Texas Siftings’ 212: She extracted a twenty dollar bill, and remarked : ‘I reckon I’ve got the dead wood on that new bonnet I’ve been sufferin’ for.’.
1894		Advocate (Topeka, KS) 28 Mar. 3/2: He laughed as does the policeman who has ‘got the deadwood’ on some poor wretch.
1903		Bulletin (Sydney) 10 Dec. 39/2: [W]id the exercise av a little ingenooity ’tis ahlways possible to git deadwood on arn’ry min loike thim.
1905		J.W. Carr ‘Words from Northwest Arkansas’ in DN III:i 77: deadwood, deady, n. Advantage, control. ‘I’ve got the deadwood/deady on you.’.
1910		Hawaiian Star (Honolulu) 28 May 7/3: Two New York Senators are bounced out for corruption, and they’ve got the deadwood on a dozen more.
1945		R.L. Bellem ‘Poison Payoff’ Hollywood Detective Dec. 🌐 But so far, I’ve never been able to get the deadwood on her.
1949		L. Glassop Lucky Palmer 156: She’s got you taped, too, kid. She’s got the wood on all of us.
1951		D. Stivens Jimmy Brockett 257: There was nothing doing there while Pat had the dead wood on Jimmy Brockett.
1968		S. Gore Holy Smoke 64: Give the Government their whack, if you can’t duck out of it – they’ve got the wood on you, anyway.
1972		G.W. Turner Eng. Lang. in Aus. and N.Z. 107: The list of items valid in both countries is a long one and would include [...] have the wood on ‘have an advantage over’.
1985		R.G. Barrett You Wouldn’t Be Dead for Quids (1989) 77: Or I can turn tail and piss off like a dingo and know some sheila’s held the wood over me.
1988		McGill Dict. of Kiwi Sl. 124/1: wood have the advantage, often to have the wood on; as in woodchopping contests, at least from 1941.
2003		McGill Reed Dict. of N.Z. Sl. [as cit. 1988].