Pronunciation GB: ˈrəʊtəsɪzm, GA: ˈroʊɾəsɪzm

(1) The use of an r sound instead of another sound, usually an apical consonant, and very often an s or z. The precise phonetic quality of the r sound depends on the language involved. In the following examples r is used as a cover symbol for all r sounds:

Some British English accents: t → r e.ɡ. getting = ˈgerɪn
Middle → Late Cornish: z → r e.g. ɪθ ˈezə vɪ (Middle = “I am”) → ˈθerə vɪ(Late)
Standard Italian ˈultimo (“last”) → Sicilian ˈurtimu.
Some Irish accents: knaːv (cnámh = “bone”) → kɾaːv

The opposite process, where an r sound is replaced by something else, might be called reverse rhotacism. This can be found in some English accents in familiar forms of personal names. For example, Baz or Bazza for the name Barry, Jez or Jezza for Jeremy, and Flossie for Florence.

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(2) Formerly in speech pathology, the inability to produce the standard r sound of an accent. A familiar example in English is the use of ʋ (voiced labiodental approximant) instead of ɹ (post-alveolar).