This article relies largely or entirely on a single source. (June 2012)
Relaxed pronunciation (also called condensed pronunciation or word slurs) is a phenomenon that happens when the syllables of common words are slurred together. It is almost always present in normal speech, in all natural languages but not in some constructed languages, such as Loglan or Lojban, which are designed so that all words are parsable.
Some shortened forms of words and phrases, such as contractions or weak forms can be considered to derive from relaxed pronunciations, but a phrase with a relaxed pronunciation is not the same as a contraction. In English, where contractions are common, they are considered part of the standard language and accordingly used in many contexts (except in very formal speech or in formal/legal writing); however, relaxed pronunciation is markedly informal in register. This is also sometimes reflected in writing: contractions have a standard written form, but relaxed pronunciations may not, outside of eye dialect.
Certain relaxed pronunciations occur only in specific grammatical contexts, the exact understanding of which can be complicated. See trace (linguistics) for some further info.
The following sections contain common words said with relaxed pronunciation in American English, along with pronunciations given in IPA, and a common written indication of this pronunciation where applicable:
The words of, to, and have all tend to elide to nothing more than a schwa [?] in many common situations. This sometimes leads to spelling confusion, such as writing "I could of..." instead of "I could have..." or "I could've".
"Would" can also be contracted ("I'd have done things differently."), which usually yields  ("I would have..." can be pronounced [a]). The [v] in "have" and "of" is usually retained before a vowel sound (e.g. in "I could have asked...").
"You" tends to elide to [j?] (often written "ya"). Softening of the preceding consonant also may occur: (/t/ + /j?/ = [t], /d/ + /j?/ = [d], /s/ + /j?/ = , and /z/ + /j?/ = ). This can also happen with other words that begin with [j] (e.g. "your", "yet", "year"). In some dialects, such as Australian English, this is not a relaxed pronunciation but compulsory: got you ['t?j?:] (never *['tj?:]).
Examples of the Dutch as spoken in the Netherlands include:
Often, especially in Belgian Dutch, the -t at the end of the word is omitted.
A wide range of possible pronunciations can be found in the negatory 'nicht ("not") depending on the dialect region.
See also Synalepha
Contracted forms are usually found only in colloquial contexts, but they can occur in poetry.
For example, look at the verse from the Russian translation of Avesta (Mihr Yasht, verse 129):
"On a side of the chariot of Mithra, the lord of wide pastures, stand a thousand ... arrows, with a golden mouth."
This contrasts with contracted forms found in colloquial speech in that it is used to keep the original rhythm. The previous verse (verse 128) has a literary form:
"On a side of the chariot of Mithra, the lord of wide pastures, stand a thousand bows well-made, with a string of cowgut".
The phrase tu as (you have) is frequently elided to t'as and tu es (you are) to t'es. The same with je suis (I am) to j'suis or ch'uis (very informal, or regional), and je [ne] sais pas (I don't know) to j'sais pas or ch'ais pas (very informal, or regional). The expression, "Qu'est-ce que..." is little used in colloquial speech for forming the interrogative, but when it is, in very informal use, it is shortened:
"Qu'est-ce que tu veux ?" becomes... "Qu'est-c'tu veux ?"
"Qu'est-ce que tu as dit?" becomes... "Qu'est-c't'as dit?"
A more complex sentence, such as "il ne savait peut-être plus ce qu'il faisait" ("Perhaps he knew no more what he was doing"), can become "i n'savait p'têt plus c'qui v'zait" [in sav?p t?t plys kiv z?], or even further relaxed, "i sa'ait têt' pu c'qui v'zait" [i sa?p t?t pys kiv z?].
As such, the d in the final -ado of past participles can disappear: Estoy cansado ("I am tired") is heard as Toy cansao; this is also applied to the final -ido, as in Me he perdido ("I got lost"), which is heard as *Me perdío. This phenomenon is often perceived as uncultured, and can lead to hypercorrections like *bacalado instead of bacalao ("cod").
Hiatus between two words will often lead to these merging, with del being the grammatically correct form of de el. If the merged word is small enough, it might be omitted entirely:
Some dialects like Andalusian Spanish lose the syllable-final s. Since it is important as a mark of plurals, it is substituted with vowel opening.
In some dialects, que (that) is reduced to the "q" sound:
In Portugal, the mute 'e' and the final unstressed vowels are often elided:
Japanese can undergo some vowel deletion or consonant mutation in relaxed speech. While these are common occurrences in the formation of some regular words, typically after the syllables ku or tsu, as in gakk? (? gaku + ? k?) "school" or shuppatsu (? shutsu + ? hatsu) "departure", in rapid speech, these changes can appear in words that did not have them before, such as suizokkan for suizokukan "aquarium." Additionally, the syllables ra, ri, ru, re and ro sometimes become simply n or when they occur before another syllable beginning with n or d, and disappear entirely before syllabic n. This can happen within a word or between words, such as wakannai "I dunno" for wakaranai "I don't know" or ? m? kite n da yo "they're already here" for m? kite iru n da yo.
Relaxed pronunciation also makes use of several contractions.
In all of these cases, the pronounced length of the initial vowel is slightly extended, though in the case of "nap?yon" the terminal vowel maintains its initial length or, if anything, is shortened.