The definition of substandard is something that does not meet a basic, established level.
Getting Ds and Fs on your report card is an example of substandard academic performance.
below standard; specif.,
- below a standard established as by law
- Linguis. nonstandard: substandard, not widely used by linguists, is a usually pejorative designation for dialects or linguistic forms that differ from the standard dialect
- Failing to meet a standard; below standard.
- Linguistics a. Of, relating to, or indicating a pattern of linguistic usage that does not conform to that of the prestige group in a speech community or to that of the standard language.b. Not in accord with notions of good English; nonstandard. See Usage Note at nonstandard.