Definition - An acronym for Received Pronunciation, the regionally-neutral British-English prestige accent.

1. It is an accent (i.e. a form of pronunciation), not a dialect (a vocabulary and rules of grammar).
2. About two percent of Britons speak its pure form.

Oxford English Dictionary -
The acronym's first citation is from 1889:
"Other Abbreviations in Frequent Use. … *rp., received pronunciation, or that of pronouncing dictionaries and educated people."
(A. J. Ellis Early Eng. Pronunc. v. 6)

Please comment