not standard
not accepted as a model of excellence "a nonstandard text"
varying from or not adhering to a standard "nonstandard windows" "envelopes of nonstandard sizes" "nonstandard lengths of board"
not conforming to the language usage of a prestige group within a community "a nonstandard dialect is one used by uneducated speakers or socially disfavored groups" "the common core of nonstandard words and phrases in folk speech"- A.R.Dunlap