Green’s Dictionary of Slang

1. an exhausted person.

1890–1904		Farmer & Henley Sl. and Its Analogues.
1896		W.C. Gore Student Sl. in Cohen (1997) 9: deader. n. A weary, or exhausted person.
1906		Times Dispatch (Richmond, VA) 9 Dec. 4/5: See that medder? / I’ve tramped it till I’m sore. / To find as I’m a deader, / It’s a moor.

2. a dead person, a corpse; thus be a deader, to be recently dead.

1901		‘Rolf Boldrewood’ In Bad Company 22: They’d be deaders the first dry season – down from weakness for a week or two, with their eyes picked out by the crows.
1916		‘Taffrail’ Pincher Martin 292: ’Ere [...] one o’ them ’ere deaders ’as come back ter life!
1929		‘Josphine Tey’ (as ‘Gordon Daviot’) Man in the Queue 31: Danny said, politely, 'That's the deader from the queue. No, I'm very sorry to disappoint you, Inspector, but I never saw the man in my life'.
1936		L. Pound ‘American Euphemisms for Dying’ in AS XI:3 198: Is a deader.
1961		(con. 1930s) D. Behan Teems of Times and Happy Returns 98: The deader is goin’ to start walking now and I’m glad I’m in the middle between Seamus and Brian.

3. (Aus.) a murderer.

2009

P. Temple Truth 61: Knowing the dead’s a step, catching the deaders, that’s the trick.