nurse merger

noun1

1. •
   A phonemic merger occuring in most present accents of English where historic /ɛr/, /ɪr/, /ʊr~ʌr/ are pronounced identically.

   • Levelling of ME /irC/ and /urC/, which Orton assumes for the whole of the North (S. Durham §§411-13), has not taken place in Dent and S.We, where ME /urC/ remains (4:46). — 1967