/huy'peuhr err"beuh niz'euhm/ , n. Ling.
a pronunciation or grammatical form or usage produced by a speaker of one dialect according to an analogical rule formed by comparison of the speaker's own usage with that of another, more prestigious, dialect and often applied in an inappropriate context, esp. in an effort to avoid sounding countrified, rural, or provincial, as in the pronunciation of the word two /tooh/ as /tyooh/ . Cf. hypercorrection, hyperform .
[ 1920-25; HYPER- + URBAN + -ISM ]