Сөз басына дыбыс қосылуы

The insertion of a sound at the beginning of a word

In linguistics, prothesis ('/p//r//ɒ//θ//ɪ//s//ɪ//s/; from post classical Latin based on πρόθεσις próthesis 'placing before'), or less commonly prosthesis (from Ancient Greek πρόσθεσις 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 prothesis is called prothetic or less commonly prosthetic. Prothesis is different from the adding of a prefix, which changes the meaning of a word. Prothesis is a metaplasm, a change in spelling or pronunciation. The opposite process, the loss of a sound from the beginning of a word, is called apheresis or aphesis.

A well known example is that + stop clusters (known as s impurum), in Latin, gained a preceding in early Romance languages (Old Spanish, Old French, Galician Portuguese). Thus, Latin status changed to Spanish estado and French état, été (in which the s was later lost) "state"/"been", and Latin speciālis changed to Spanish and Old French especial (Modern French spécial and Italian speciale).

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, borrowed from French, becomes Turkish istasyon. Similarly, in Bashkir, a prosthetic vowel is added to Russian loanwords if a consonant or a consonant cluster appears at the beginning: арыш "rye" from Russian рожь, өҫтәл "table" from Russian стол, эскәмйә "bench" from Russian скамья, etc. However, Bashkir presents cases of novel prothesis in terms that are inherited from Old Turkic: ыласын "falcon" from Old Turkic lačïn, ысыҡ "dew" from Old Turkic čïq.

In Nenets, Enets and Nganasan, prothesis of a velar nasal before vowels has occurred historically: the Nenets words "road", "bow" are cognate with Hungarian út, íj with the same meaning. In some varieties of Nenets, the rule remains productive: the initial syllable cannot start with a vowel, and vowel initial loanwords are adapted with prothetic .

Hindi words from English have an initial i before sp , sk or sm : school → iskuul, special → ispesal, stop → istahp.

In Persian, loanwords with an initial sp , st , sk or sm add a short vowel e at the beginning: spray → esprey, stadium → estadiun, Stalin → Estalin, skate → eskeyt, scan → eskan, etc.

During their evolution from Proto Slavic, words in some Slavic languages gained a prothetic /v/ (spelled "w" in Polish). Proto Slavic *okъno ("window") vs. Ukrainian vikno, Belarusian vakno, Common Czech vokno
Proto Slavic *ǫtroba ("internal organs") vs. Polish wątroba ("liver")

Some Semitic languages, such as Arabic and Hebrew, regularly break up initial two consonant clusters by adding a prothetic vowel. The vowel may be preceded by the glottal stop /ʔ/ (see aleph) or, in Hebrew, /h/, which may be pronounced or simply written. Because of the triconsonantal root morphology of Semitic languages, the prothetic vowel may appear regularly when the first two consonants of the root lack an intermediate vowel, such as in verb conjugation: Arabic ʼaktubu (I write) from the verb kataba (root ktb). In Hebrew, prothesis occurs in nouns of Greek origin, such as Aplaton (Plato), itztadion (stadium).

Welsh features h prothesis only for vowel initial words. It occurs in words after ei 'her', ein 'our', and eu 'their': oedran 'age' ei hoedran 'her age'. It also occurs with ugain 'twenty' following ar (on) in the traditional counting system: un ar hugain 'twenty one' (literally, 'one on twenty').

Swiss German features n prothesis if a word ends with a vowel and the next word begins with a vowel. A dropped final n was originally retained then, but the process now occurs in contexts in which n never existed. A similar process called intrusive r occurs in some varieties of English.

A prothetic vowel performs external sandhi in Italian: compare la scuola ("the school") vs. in iscuola ("at school"). It is, therefore, conjectured both that the origins of the Romance prothesis are phonetical, rather than grammatical. Prothesis originally broke consonant clusters if the preceding word ended in a consonant. There was no prothesis in the Romance dialects that had lost their terminal consonants.

Phonetic rules of a native language may influence the pronunciation of a second language, including various metaplasms. For example, prothesis is reported for Crimean Tatars when they speak Russian. 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".