Dis
1980s: abbreviation of disrespect.
wiktionary
Abbreviation of disrespect.
Learned borrowing from Old Norse dís.
Representing a colloquial or dialectal pronunciation of this.
etymonline
dis (v.)
also diss, slang, by 1980, shortening of disrespect or dismiss, originally in African-American vernacular, popularized by hip hop. Related: Dissed; dissing. Earlier it was short for distribute in late 19c. printers' slang and for disconnected in the telephone-line sense, and in this sense it was given a slang figurative extension as "weak in the head" (1925).
Dis
Roman underworld god, from Latin Dis, contracted from dives "rich," which is related to divus "divine, god" (from PIE root *dyeu- "to shine," in derivatives "sky, heaven, god"), hence "favored by god." Compare Pluto and Old Church Slavonic bogatu "rich," from bogu "god."