not conforming in pronunciation, grammar, vocabulary, etc., to the usage characteristic of and considered acceptable by most educated native speakers; lacking in social prestige or regionally or socially limited in use: a nonstandard dialect; nonstandard English. Compare standard(def. 27).
3.
Mathematics. of or pertaining to a generalized system of numbers that includes the real numbers but also includes infinite and infinitesimal numbers: nonstandard analysis.
Varying from or not adhering to the standard: nonstandard lengths of board.
Linguistics Associated with a language variety used by uneducated speakers or socially disfavored groups.
Usage Note: The term nonstandard was introduced by linguists and lexicographers to describe usages and language varieties that had previously been labeled with terms such as vulgar and illiterate. Nonstandard is not simply a euphemism but reflects the empirical discovery that the varieties used by low-prestige groups have rich and systematic grammatical structures and that their stigmatization more often reflects a judgment about their speakers rather than any inherent deficiencies in logic or expressive power. Note, however, that the use of nonstandard forms is not necessarily restricted to the communities with which they are associated in the public mind. Many educated speakers freely use forms such as can't hardly or ain't I to set a popular or informal tone. · Some dictionaries use the term substandard to describe forms, such as ain't, associated with uneducated speech, while reserving nonstandard for forms such as irregardless, which are common in writing but are still regarded by many as uneducated. But substandard is itself susceptible of disparaging interpretation, and most linguists and lexicographers now use only nonstandard, the practice followed in this Dictionary.
[non-stan-derd] 
dərd