|Sound change and alternation|
In linguistics, prothesis (from post-classical Latin based on Ancient Greek próthesis 'placing before'), or less commonly prosthesis (from Ancient Greek prósthesis 'addition') is the addition of a sound or syllable at the beginning of a word without changing the word's meaning or the rest of its structure. A vowel or consonant added by prosthesis is called prothetic or prosthetic.
Prothesis is different from the adding of a prefix, which changes the meaning of a word.
A well-known example: /s/ + stop clusters (known as s impurum) in Latin gained a preceding /e/ in early Romance languages (Old Spanish, Old French). Hence, Latin status changed to Spanish estado and French état/été (in which the s was lost) "state"/"been", and Latin speciālis changed to Spanish and Old French especial (Modern French and English special).
Some Turkic languages avoid certain combinations of consonants at the beginning of a word. In Turkish, for instance, Smyrna is called İzmir, and the word station, being borrowed from French becomes Turkish istasyon.
Similarly, in Bashkir language a prosthetic vowel is added to Russian loanwords where a consonant or a consonant cluster appear at the beginning: арыш "rye" from Russian рожь "id.", өҫтәл "table" from Russian стол "id.", эскәмйә "bench" from Russian скамья "id.", etc. More interestingly, however, Bashkir presents cases of novel prothesis in terms inherited from Common Turkic, i.e. ыласын "falcon" from Old Turkic lačïn "id.", ыcыҡ "dew" from Old Turkic čïq "id.", etc.
In the Samoyedic languages Nenets, Enets and Nganasan, a prothesis of a velar nasal [ŋ] before vowels has occurred historically. For example, the Nenets words /ŋuːʔ/ "road", /ŋin/ "bow" are cognate with Hungarian út, íj, of the same meaning.
In the Persian language in loan words with initial sp-, st-, sk- or sm- clusters a short vowel e is added in the beginning: spray→esprey, stadium →estadiun, Stalin → Estalin, skate→eskeyt, scan→eskan etc.
Example for pronunciation of initial sm- cluster by Persian language speakers: Persians learning Polish pronounce the word smacznego (bon appétit) as esmacznego.
During the evolution from the Proto-Slavic language words in various Slavic languages employed pro(s)thetic consonants. Compare: Russian okno ("window") vs. Ukrainian vikno or Belarusian vakno. Another example: Polish wątroba ("liver sausage") from PS ǫtroba (cf. Russian utroba).
Examples of a pro(s)thetic vowel performing external sandhi are known, e.g., in Italian language. Compare: la scuola ("the school") vs. in iscuola ("at school"). It is therefore conjectured that the origins of the Romance prothesis are phonetical ones, rather than grammatical ones, and initially prothesis was for breaking consonant clusters with the preceding word ending in consonant. This hypothesis is corroborated by the absence of prothesis in Romance dialects that had lost their terminal consonants 
Phonetic rules of the native language may influence pronunciation of a second language, including various metaplasms. For example, prothesis is reported for Crimean Tatars speaking Russian language.
James L. Barker writes:"If an Arab, an East Indian, a Frenchman, Spaniard, or Italian is given the following sentence to read: I want to speak Spanish, he reads it in the following manner: I want to speak (i)/(e)Spanish. In this case there is no 'parasitic' i or e before sp of speak, but there is before sp in Spanish".
Notes and references
- "prothesis". Oxford English Dictionary (3rd ed.). Oxford University Press. September 2005.
- Merriam-Webster Dictionary prothesis
- πρόθεσις. Liddell, Henry George; Scott, Robert; A Greek–English Lexicon at the Perseus Project
- Trask, Robert Lawrence. 1999. A Dictionary of Phonetics and Phonology. London: Routledge, p. 296.
- Merriam-Webster Dictionary prosthesis,
- πρόσθεσις. Liddell, Henry George; Scott, Robert; A Greek–English Lexicon at the Perseus Project
- Heinrich Lausberg, "Romanische Sprachwissenschaft" ("Romance Linguistics"), Vol. 1, Berlin, 1956, pp.64-65 (German)
- Paul V. Cubberley, "Russian: A Linguistic Introduction" (2002) ISBN 0521796415, p.35, books.google.com
- Richard D. Janda & Brian D. Joseph, "Reconsidering the Canons of Sound-Change: Towards a “Big Bang” Theory", in: "Historical Linguistics 2001. Selected Papers from the 15 International Conference on Historical Linguistics, Melbourne, 13–17 August 2001", Amsterdam: John Benjamins Publishing Co. (2003), pp. 205-219
- "Crimean Tatar-Russian as a Reflection of Crimean Tatar National Identity", iccrimea.org
- James L. Barker, "Accessory Vowels (Voyelles prostetiques et autres)", Modern Language Notes, Vol. 40, No. 3 (March 1925), pp. 162-164; p.162, links.jstor.org
- Andrei A. Avram, "On the Status of Prothetic Vowels in the Atlantic French Creoles" (pdf file), Antwerp Papers in Linguistics, Issue 107 (2004), ua.ac.be