Def was college slang for definitive- the last word, the best, etc.

Almost no urban slang here. Very few African-Americans, and they are business or ranch people, 3 or more generations here. Ethiopians, Somalis, West Indians, etc. have their own slang or have abandoned it. Some 300 Congolese, but their language is French.

Owned pretty much is used in the English or UK sense here. Owned in the sense of controlled goes way back before computers (17th c.). It is not considered slang.
Ownage goes back to the 16th c. -the fact of owning.

Urban dictionary (at least to this non-eastern city person) looks like it makes a good try at keeping up with kids' slang.
Wikipedia is a notorious source of mis-information.

Dis, of course, is abbreviated disparage. Few seem to use it in its older sense of disconnected, or mentally feeble.