Green’s Dictionary of Slang

a prior conviction, a criminal record; often in pl. priors.

1895		Herald (Melbourne) 27 Aug. 2/8: But they chose to go before his nibs, and the twelve godfathers (jury). As they had a ‘prior’ or two against them they were sent on the station for three years.
1939		R. Chandler Big Sleep 53: He’s got a prior back in Indiana, attempted hold-up six years ago.
1970		J. Wambaugh New Centurions 272: ‘You know petty theft with a prior is a felony’.
1990		S. Morgan Homeboy 85: The lady judge bumped up her felony docket on account of all her priors.
1996		(con. 1964-65) B. Thorpe Sex and Thugs and Rock ’n’ Roll 71: ‘Do you have any priors, son?’.
2000		G. Pelecanos Shame the Devil 36: Weston’s a known low-level dealer with priors.
2005		M.B. ‘Chopper’ Read Chopper 4 196: Two of them [i.e. arrestees] have quite decent priors.
2012		G. Pelecanos (con. 1972) What It Was 124: I ran Alonzo Jefferson through the syustem. He’s got priors.
2021		S.A. Crosby Razorblade Tears 105: Ike had a prior for manslaughter.