Th-fronting is a merger that occurs (historically independently) in Cockney, Newfoundland English, African American Vernacular English, and Liberian English (though the details differ among those accents), by which Early Modern English /θ, ð/ merge with /f, v/. Apparently, no accents with the merger completely merge the phonemes, because virtually all speakers of such accents know which words "should" have which sound; moreover, in many accents the two sounds appear in free variati… (More on Th-fronting)