|Sound change and alternation|
- the excessive or idiosyncratic use of the r;
- the inability to pronounce (or difficulty in pronouncing) r.
- the conversion of another consonant into r.
In medicine, rhotacism is the inability or difficulty in pronouncing the sound r. In English, the most common occurrence of this type is a pronunciation perceived as closer to [w]. The Looney Tunes character Elmer Fudd is notorious for his exaggerated rotacistic speech, as in, "Be vewy quiet: I'm hunting wabbits." The cartoon characters Homestar Runner and Tweety talk in much the same way. Another example is the depiction of Pontius Pilate in Monty Python's Life of Brian. In the Only Fools and Horses episode Stage Fright, a singer's rhotacism is a central plot device. In popular culture, examples include Barry Kripke (from The Big Bang Theory), Roy Hodgson, Edward Ka-Spel, Matt Bellamy, Jonathan Ross, Brian Walden, David Zayas, Frank Muir, Sister Wendy Beckett, Lucy Worsley, Terry Jones, and the politicians Roy Jenkins and Michael Heseltine. Other examples are interviewer Barbara Walters actresses Kay Francis and Marlene Dietrich and King George VI.
Rhotacism is more common among speakers of languages that have a trilled R, such as Swedish (except in the landscapes of Skåne, Halland, Blekinge, Öland and southern Småland), Finnish, Italian, Polish, and Spanish. This sound is usually the last one a child masters. Some people never learn to produce it; they substitute other sounds, such as the velar approximant, the uvular approximant, and the uvular trill (often called "French R").
Many speech pathologists call this problem de-rhotacization, because the sounds lose their rhotic quality rather than becoming rhotic.
In linguistics, rhotacism or rhotacization is the conversion of a consonant (usually a voiced alveolar consonant — /z/, /d/, /l/, or /n/) to a rhotic consonant in a certain environment. The most common may be of /z/ to /r/.
- zëri vs. zâni 'the voice'
- gjuri vs. gjuni 'the knee'
- Shqipëri vs. Shqypni 'Albania'
- i gëzuar vs. i gëzuam 'happy'
- i tretur vs. i tretun 'lost'
In Aramaic, proto-Semitic n is often changed to r:
- bar "son" as compared to Hebrew ben (from Proto-Semitic *bnu)
- trên and tartên "two" (masculine and feminine form respectively) as compared to Demotic Arabic tnēn and tintēn (from Proto-Semitic *ṯnaimi and *ṯnataimi). Cf. also Aramic tinyânâ "the second one", without the shift.
Irish and Scots Gaelic 
Germanic languages 
All surviving Germanic languages, members of the North and West Germanic families, underwent a change of /z/ to /r/, implying a more approximant-like rhotic consonant in early Germanic. Some languages have regularized, giving all forms an r. Gothic retains s or z, since it did not undergo rhotacism.
|Proto-Germanic||Gothic||Old Norse||Old English
|Old Frisian||Dutch||(Old High German)
|*was,1st/3rd sg *wēzun1st pl||was, wēsum
|*fraleusaną,inf *fraluzanazp.part.||fraliusan, fralusans
Pronouncing the letter "r" is common in many dialects of American, Canadian, Irish, Welsh and Scottish English and less common in the English of most of England, Australia, and New Zealand.[dubious ] Lenition of intervocalic /t/ and /d/ to [d] or [ɾ] is also common in many modern English dialects (e.g. <got a lot of> (phonemically /gotə lotə/) becoming [godə lodə] or [goɾə loɾə]). Contrast is maintained with /ɹ/ because it is never realized as a flap in English.
In Central German dialects, esp. Rhine-Franconian and Hessian, /d/ is frequently realized as [ɾ] in intervocalic position. This change also occurs in Mecklenburg dialects.
- Borrem (Central Hessian) vs Boden (Standard German)
Romance languages 
- flōsnom — flōremacc (Old Latin flōsem)
- genusnom — generisgen (from *geneses, cf. Sanskrit janasas)
- rōbus, rōbustus — rōbur, corrōborāre (verb from *conrobosare)
- jūstus — de jūre (from de jouse)
- est — erō (from esō)
This reflects a highly regular change in pre-classical Latin. Intervocalic s in the oldest attested Latin documents (assumed to have been pronounced /z/) invariably became r. Intervocalic s in Classical Latin suggests either borrowing (e.g. rōsa) or reduction of an earlier ss (e.g. pausa < paussa, vīsum < *vīssum < *weid-tom). Old s was preserved initially (septum), finally, and in consonant clusters.
The English word honour or honor is derived from Anglo-Norman honour, which in turn was derived from Late Latin honor, earlier honos, which became honor by analogy with the oblique stem of honoris (genitive).
The consonants d or l changed to r before another d or l, so that the same consonant would not appear twice in a row (dissimilation).
- medius — merīdiēs (from *medi-diēs)
- caelum — caeruleus (from *cael-uleus)
This phenomenon was noted by the Romans themselves:
In many words in which the ancients said s, they later said r... foedesum foederum, plusima plurima, meliosem meliorem, asenam arenam—Varr. De lingua Latina, VII, 26, In multis verbis, in quo antiqui dicebant s, postea dicunt r... foedesum foederum, plusima plurima, meliosem meliorem, asenam arenam
In Neapolitan rhotacism is seen in a shift from the sound of "d" to an "r" sound:
(Italian vs Neapolitan)
- medesimo vs meresemo
- diaspora vs riaspro
- madonna vs maronna
and, to a lesser extent, from the sound of an "l" to an "r" sound:
- albero vs arvero
- ultimo vs urdemo
In Old Portuguese, rhotacism occurred from the «l» sound to the «r» sound, mainly in consonant plus el clusters, as in the words obrigado, "thank you", originarily from "obliged [in honorably serving my Sir]", praia, "beach", prato, "plate" or "dish", branco, "white", prazer, "pleasure", and praça, "square". In other instances, l-vocalization happened instead, as in céu, "sky".
In contemporary Brazilian Portuguese, rhotacism of /l/ in the syllable coda is characteristic of the caipira dialect, while further rhotacism in the nationwide Vernacular include planta, "plant", as [ˈpɾɐ̃tɐ], lava, "lava", as /ˈlarvɐ/ (thus homophonous with larva, worm/maggot), lagarto, "lizard", as [laʁˈgaʁtu] (in dialects with guttural coda r instead of a tap) and advogado, "lawyer", as [ɐ̞de̞vo̞ʁˈgadu]. These non-standard patterns are largely marginalized, as rhotacism is regarded as either sign of speech-language pathology or part of the characteristics of illiterates' speech.
Rhotacism in Romanesco consists of a shift from "l" to "r" when it is followed by a consonant, similar to what occurs in certain Andalusian dialects of Spanish. Thus, Latin altus (tall) which in Italian is alto in Romanesco becomes arto. In ancient Romanesco it also happened when "l" was preceded by a consonant, as in the word ingrese (English), but the modern way of speaking has lost this characteristic.
Another change related to r was the shortening of the geminated rr. This is not rhotacism. So the words errore, guerra and marrone (error, war, brown) in Romanesco become erore, guera and marone.
Romanian rhotacism consists of a shift from intervocalic "l" to "r" and "n" to "r".
Thus, Latin caelum (meaning 'heaven' or 'sky') became Romanian cer, Latin fenestra (meaning 'window') becomes Romanian fereastră, and Latin felicitas (meaning 'happiness') Romanian fericire.
Some northern Romanian dialects and Istro-Romanian also further transformed all intervocalic [n] into [ɾ]. This occurred only with words of Latin origin. For example, Latin bonus became Istro-Romanian bur, as compared to standard Daco-Romanian bun.
- naus (before p/t/k) vs naur bharati
- agnis (before p/t/k) vs agnir mata
This is not a case of rhotacism proper, since r and s are simply allophones in those positions.
South Slavic languages 
(This section relies on the treatment in Greenberg 1999)
In the South Slavic languages (Slovene, Croatian, Bosnian, Serbian, Macedonian, Bulgarian) rhotacism consists of the change from a voiced palatal fricative [ʒ] to a dental/alveolar tap or trill [r], usually occurring between two mid-vowels, e.g.:
- moreš (Serbo-Croatian, dial.) 'you can' from earlier možeši
- kdor (Slovene) from earlier kъto-že
The beginning of the change is attested in the Freising manuscripts, a written document from the 10th century AD, which shows both the archaism (ise 'which' < *jь-že) and the innovation (tere 'also' < *te-že). It is also found in individual lexical items in Bulgarian dialects, e.g., дорде 'until' (< *do-že-dĕ), and Macedonian, e.g. сеѓере (arch. 'always'). However, the results of the sound change have largely been reversed by lexical replacement in dialects in Serbia and Bosnia beginning in the fourteenth century. Dialects in Croatia and Slovenia have not only preserved more of the lexical items with the change, but have extended grammatical markers in -r- from heterogeneous sources that formally merged with the rhotic forms that arose due to the sound change, e.g., Slovene dialect nocor 'tonight' (< *not'ь-sь-ǫ- + -r-) on the model of večer 'evening' (< *večerъ). The reversal of the change is evident in dialects in Serbia where the -r- formant is systematically removed, e.g., Serbian veče 'evening'.
This phenomenon appears in Andalusian Spanish (particularly in Seville, where "l"s at the end of a syllable preceding another consonant are replaced with "r"s, e.g. saying "Huerva" instead of "Huelva". The reverse is done in Caribbean dialects, even at the beginning of words, e.g. saying "Puelto Lico" instead of "Puerto Rico".
- Catford (2001:178)
- Trask, R. Larry (2008), in Wheeler, A Historical Dictionary of Basque, University of Essex, p. 29, retrieved January 22, 2011
- Catford (2001:179)
- D. Hofmann, A.T. Popkema, Altfriesisches Handwörterbuch (Heidelberg 2008).
- robus1; rōbur. Charlton T. Lewis and Charles Short. A Latin Dictionary on Perseus Project.
- Nandris (1963:255–258)
- Greenberg (1999)
- Catford, J.C. (2001), "On Rs, rhotacism and paleophony", Journal of the International Phonetic Association 31 (2): 171–185, doi:10.1017/S0025100301002018
- Crowley, Terry. (1997) An Introduction to Historical Linguistics. 3rd edition. Oxford University Press.
- Greenberg, Marc L. (1999), "Multiple Causation in the Spread and Reversal of a Sound Change: Rhotacism in South Slavic", Slovenski jezik/Slovene Linguistics Studies 2: 63–76 http://hdl.handle.net/1808/803
- Nandris, O (1963), Phonétique Historique du Roumain, Paris: Klincksiek