Green’s Dictionary of Slang

1. one who shirks work or avoids exertion etc.

1899		Daily Tel. 14 Aug. in Ware (1909) 122/2: Every man after lunch devotes himself to ‘eccer’, which is, in ordinary parlance, exercise. This may take the shape of ‘footer’, or a mild constitutional known as a ‘constituter’, while if any one lounges idly about he is, of course, a ‘slacker’.
1908		Magnet 29 Feb. 3: ‘Cad!’ ‘Slacker!’ ‘Rotter!’.
1912		A. Brazil Fourth Form Friendship 17: ‘I’ve often heard you say yourself that if one is to get on at school one must do well at games.’ ‘No one tolerates slackers, certainly I’ll allow that’.
1914		‘Bartimeus’ ‘The Argonauts’ in Naval Occasions 37: What about a song, you slacker! Something with a chorus.
1919		Seattle Star (WA) 7 June 10/3: Oh! Woody! Pay Up your Taxes! [...] Discovery has been made that President Wilson is a slacker — a tax slacker.
1929		E. Booth Stealing Through Life 239: But I was a slacker; I was a deserter.
1932		(con. 1917–19) Dos Passos Nineteen Nineteen in USA (1966) 467: The crowd [...] yelled ‘Slackers’ at them and the girls hissed and booed.
1939		K. Tennant Foveaux 95: There are too many slackers and rotters leaning against lamp-posts while the boys in the trenches are crying out in vain for reinforcements.
1942		Whizzbang Comics 76: And that bunch of stuffed scarecrows at the house taking you for a mug or a slacker!
1947		B. Schulberg Harder They Fall (1971) 181: Carpentier the war hero versus Dempsey the slacker.
1950		A. Buckeridge Jennings Goes To School 58: Venables, you dirty slacker, you haven’t washed your feet!
1958		H.S. Thompson letter 17 Jan. in Proud Highway (1997) 101: A slacker’s credo for pleasure.
1968		P. Barnes Ruling Class Prologue: The Gurneys have never been slackers.
1977		L. Heinemann Close Quarters (1987) 155: You two slackers are in plenty, plenty trouble.
1989		H. Rawson Dict. of Invective (1991) 358: slacker. One who shirks work or evades other obligations, especially during time of war.
2000		Guardian G2 20 Jan. 14: A US site dedicated to ‘slackers, goof-offs, procrastinators, loafers, long lunchers and web-addicted employees world wide.’.

2. (orig. US) a member of the generation in their 20s (c.1995) who, for whatever reason, perhaps cynicism or indolence, sees no point in joining the social mainstream; also attrib.

1990		Commercial Appeal (Memphis, TN) 29 Aug. C5: Here was the full range of Austin lifestyles – old hippies, [...] middle-age black professionals, underachieving writers and musicians known around town as ‘slackers’, [etc.].
1999		Guardian Media 6 Sept. 8: The latest thing is the ‘slackcom’ – the sitcom for the slacker generation.
1999		Indep. on Sun. Culture 13 June 8: The height of their ambition is to be nothing more than grungey slackers.
2000		C. Cook Robbers (2001) 3: Austin, state capital, university town. Former counterculture magnet and slacker haven.