Green’s Dictionary of Slang

dis v.

also diss

1. to disparage, to attack verbally.

[Aus]Sun. Times (Perth) 10 Dec. 4/8: When a journalistic rival tries to ‘dis’ you / And to prejudice you in the public’s eyes.
[US]Cold Crush Bros ‘Fresh Wild Fly and Bold’ [lyrics] Kiss his woman, dis his mother, and don’t even run.
[US]Run DMC ‘Rock Box’ [lyrics] We’ll diss a sucker MC make the other suckers hate it.
[US]Eble Campus Sl. Nov. 3: dis – criticize.
[US]G. Tate ‘Michael Jackson’ in Flyboy in the Buttermilk (1992) 97: Young black men and women who conceive of their African inheritance as little more than a means to cold-crash mainstream America and then cold-dis [...] the brothers and sisters left behind.
[US]G. Tate ‘The GOP Throws a Mammy-Jammy’ in Flyboy in the Buttermilk (1992) 100: Need I spell out what effect Dukakis’s dissing of Jesse and the entire African-American body politic did to turn her stomach?
[WI]Pinchers ‘Bandolero’ [lyrics] You should never dis the champion.
[UK]T. Hill Underground 7: Oy. Don’t diss my team, all right?
[UK]Guardian Rev. 1 Jan. 18: Why you be always dissin’ the RAC?
[US](con. 1990s) in J. Miller One of the Guys 111: ‘Don’t let nobody diss your set’.
[US]C.W. Ford Deuce’s Wild 27: T-Mo dissed al-Salaam for converting to Islam.
Kon-shens ‘Bad Girl’ [lyrics] Gyal weh nuh fraid if a gyal diss you or diss your friend.
[UK]Guardian 23 Sept. 11/4: Mocking straights, ‘faggots’ and Lesbians, midgets, ‘fat girls’ [...] whichever minority she’s just dissed.

2. to disrespect.

[US]Eble Campus Sl. Oct. 2: dis – not show proper respect.
[US]L. Bing Do or Die (1992) 3: You got to be ready to do anything if somebody dis’ your hood.
[UK]J. Cameron It Was An Accident 227: Only you got your face to think about and they surely dissed me.
[UK]G. Malkani Londonstani (2007) 56: Hardjit would’ve smacked them for dissin him, dissin his house, dissin his mum’s magazines, dissin the poster.
[US]NY Times 14 Jan. [Internet] The meaning of ‘diss’ [is] to ‘dismiss’ or ‘disrespect’ someone.

3. to denigrate someone in public to the extent that it makes that person feel bad.

[US]Ice-T ‘Personal’ [lyrics] I never diss an emcee, wish ’em all good luck.
[US] Hip-Hop Connection Dec. 8: And it’s even worse when rappers name journalists and dis them publicly.
[US]A.N. LeBlanc Random Family 128: The police would have seen him naked. Roxanne had been dissed.

4. to deliberately break an appointment or date without consulting the second party.

[US]Eble Campus Sl. Apr. 3: diss – ignore, get rid of [...] ‘I got dissed hard last night. My date didn’t show up, and he didn’t call or anything.’.
[US]N. Green Shooting Dr. Jack (2002) 73: Tuco held out on him, dissed him in subtle ways, made him call a few times.

5. to inform.

[UK]Observer 18 July 10: They say she was dissing on the Park Lane gang. Informer. But she never.

In phrases

dis de program (v.) [sense 1 above + abbr. SE dis(rupt) + SAmE program (UK programme)]

(W.I./UK black teen) to put a planned thing on hold, to delay something, to disrupt a schedule.

[WI]Francis-Jackson Official Dancehall Dict. 17: Dis de program to show disregard, disrespect.
sneak disser (n.)

(US black) one who offers disrepect in a covert manner, e.g. in a rap lyric surreptitiously aimed at a rival.

Chief Keef ‘I Don’t Like’ [lyrics] Sneak dissers, that's that shit I don’t like.