Definition of mounseer in US English:

mounseer

noun

slang, rare, depreciative, archaic
  • A Frenchman.

Origin

Mid 18th century; earliest use found in The Gentleman's Magazine. Representing an archaic pronunciation of French monsieur monsieur which survived as a colloquialism down to the 19th cent., and occasionally appears in colloquial speech or in pejorative contexts with reference to English prejudice against foreigners.

Pronunciation

mounseer

/maʊnˈsɪə/