n. — abbreviation (clipping), student slang, Housing, Education
a university or college residence.
Type: 1. Origin — The shortening originally used to be res, but has changed more recently to rez, which is today's majority variant (see quotations, especially the 1991 quotation). As Chart 1 shows, the phrase in rez (as opposed to on rez, short for on a reserve is most common in Canada, and almost four times as frequent as in the US.
See also COD-2, s.v. "res2", which is labelled "Cdn slang".
See also: res
- The term is most often used in speech, rather than in writing, but see the quotations.
Images:

Chart 1: Internet Domain Search, 22 Jun. 2016