Green’s Dictionary of Slang

1. (US black) a fellow black person.

1968		‘Sl. of Watts’ in Current Sl. III:2.
1969		B. Beckham My Main Mother 148: You cats could be from Brooklyn, and shit, except for that funny-assed way you talk. You splids sound like the British are coming, and shit.
1972		T.M. Kochman ‘The Kinetic Element in Black Idiom’ in Kochman Rappin’ and Stylin’ Out 169: ‘Boot’ [...] is often used as a nickname by blacks, and as a term which, like ‘blood,’ ‘brother,’ or ‘splib,’ refers to blacks in general.
1972		K. Johnson ‘Vocab. of Race’ in Kochman Rappin’ and Stylin’ Out 148: Spliv or Splib. Can be pronounced either way.
1992		Bentley & Corbett Prison Sl. 56: Splib A black person.
2004		J. Ellroy ‘Hollywood Fuck Pad’ in Destination: Morgue! (2004) 205: O.J. was a Westside splib.

2. a derog. term for a black person [note def. ‘a liberal black who looks angry but will not upset the status quo’ (American Speech XLIX, 1976)].

1970		Atlantic Monthly Jan. 38: Any other terms such as ‘boy,’ ‘spook,’ ‘splib,’ ‘negro,’ ‘Uncle Tom,’ ‘nigra,’ ‘nigger,’ or ‘colored’ carry connotations of prejudice.
1978		J. Webb Fields of Fire (1980) 86: Well, I know how you must feel about splibs, huh Lieutenant?
1986		J. Ellroy Silent Terror 151: [‘M]y buddy moves to Chicago and gets married [...] we haven't seen each other since the day the splibs got sentenced to Life’.

3. a drunkard.

1971

H.E. Roberts Third Ear n.p.: splib n. [...] sometimes used for a drunk person.