non-U
adjective /ˌnɒn ˈjuː/
/ˌnɑːn ˈjuː/
(old-fashioned, informal)- (of language or social behaviour) not considered socially acceptable among the upper classesCultureThe terms U (= upper class) and non-U (= not upper class) were first used by an English professor in 1954 to discuss the speaking habits of English people, but they were made popular and their meaning was extended by Nancy Mitford in her book Noblesse Oblige (1956).Word OriginFrom the abbreviation U for ‘upper class’.