hyperlect
The variety of a language that is spoken by the aristocracy.
Quite distinct from received pronunciation or BBC English, hyperlect now sounds, in our more egalitarian sonic society, affected and outdated, and has largely been abandoned by the younger generation in favour of a more neutral version, either based on radio and television speak, the over-voice of documentaries, what used to be called 'speaking nicely', or a version of so-called Estuary English.
Where it comes from
From hyper- + -lect, Ancient Greek affixes meaning literally “overspeech”, that is, the speech of the overclass.
Adapted from the Wiktionary entry hyperlect (CC BY-SA 4.0).