The glottal stop is a type of consonantal sound used in many spoken languages, produced by obstructing airflow in the vocal tract or, more precisely, the glottis. The symbol in the International Phonetic Alphabet that represents this sound is ⟨?⟩. Using IPA, this sound is known as a glottal plosive.
As a result of the obstruction of the airflow in the glottis, the glottal vibration either stops or becomes irregular with a low rate and sudden drop in intensity.
In the traditional Romanization of many languages, such as Arabic, the glottal stop is transcribed with an apostrophe, ⟨'⟩, which is the source of the IPA character ⟨?⟩. In many Polynesian languages that use the Latin alphabet, however, the glottal stop is written with a reversed apostrophe, ⟨ʻ⟩ (called 'okina in Hawaiian and Samoan), which is used to transcribe the Arabic ayin as well and is the source of the IPA character for the voiced pharyngeal fricative ⟨?⟩. In Malay the glottal stop is represented by the letter ⟨k⟩, in Võro and Maltese by ⟨q⟩.
Other scripts also have letters used for representing the glottal stop, such as the Hebrew letter aleph ⟨?⟩ and the Cyrillic letter palochka ⟨?⟩, used in several Caucasian languages. In Tundra Nenets, it is represented by the letters apostrophe ⟨'⟩ and double apostrophe ⟨?⟩. In Japanese, glottal stops occur at the end of interjections of surprise or anger and are represented by the character ⟨?⟩.
In the graphic representation of most Philippine languages, the glottal stop has no consistent symbolization. In most cases, however, a word that begins with a vowel-letter (Tagalog aso, "dog") is always pronounced with an unrepresented glottal stop before that vowel (as in Modern German and Hausa). Some orthographies use a hyphen instead of the reverse apostrophe if the glottal stop occurs in the middle of the word (Tagalog pag-ibig, "love"; or Visayan gabi-i, "night"). If it occurs in the end of a Tagalog word, the last vowel is written with a circumflex accent (known as the pakupyâ) if both a stress and a glottal stop occur in the final vowel (basâ, "wet") or a grave accent (known as the paiwà) if the glottal stop occurs at the final vowel, but the stress occurs at the penultimate syllable (batà, "child").
Some Canadian indigenous languages have adopted the phonetic symbol ? itself as part of their orthographies. In some of them, it occurs as a pair of uppercase and lowercase characters, ? and ?. The numeral 7 is sometimes substituted for ? and is preferred in some languages such as Squamish.
In 2015, two women in the Northwest Territories challenged the territorial government over its refusal to permit them to use the ? character in their daughters' names: Sahai?a, a Chipewyan name, and Sakae?ah, a Slavey name (the two names are actually cognates). The territory argued that territorial and federal identity documents were unable to accommodate the character. The women registered the names with hyphens instead of the ?, while continuing to challenge the policy.
Use of the glottal stop is a distinct characteristic of the Southern Mainland Argyll dialects of Scottish Gaelic. In such a dialect, the standard Gaelic phrase Tha Gàidhlig agam ("I speak Gaelic"), would be rendered Tha Gàidhlig a'am.
In English, the (phonemic) glottal stop occurs as an open juncture (for example, between the vowel sounds in uh-oh!,) and allophonically in T-glottalization. In British English, the glottal stop is most familiar in the Cockney pronunciation of "butter" as "bu'er". Additionally, there is the glottal stop as a null onset for English, in other words, it is the non-phonemic glottal stop occurring before isolated or initial vowels (for example, representing uh-oh!, ['o?] and ['o?] are phonemically identical to /'?.o?/).
Although this segment is not a writtenphoneme in English, it occurs phonetically in nearly all dialects of English, as an allophone of /t/ in the syllable coda. Speakers of Cockney, Scottish English and several other British dialects also pronounce an intervocalic /t/ between vowels as in city. In Received Pronunciation, a glottal stop is inserted before a tautosyllabic voiceless stop: sto'p, tha't, kno'ck, wa'tch, also lea'p, soa'k, hel'p, pin'ch.
In many languages that do not allow a sequence of vowels, such as Persian, the glottal stop may be used to break up such a hiatus. There are intricate interactions between falling tone and the glottal stop in the histories of such languages as Danish (see stød), Chinese and Thai.
In many languages, the unstressed intervocalic allophone of the glottal stop is a creaky-voiced glottal approximant. It is known to be contrastive in only one language, Gimi, in which it is the voiced equivalent of the stop.
The table below demonstrates how widely the sound of glottal stop is found among the world's spoken languages. It is not intended to be a complete list. Any of these languages may have varieties not represented in the table.
|Abkhaz||[?aj]||'no'||See Abkhaz phonology.|
|Arabic||Modern Standard||||[?a'?a:ni:]||'songs'||See Arabic phonology, Hamza.|
|Metropolitan||||['?ææ]||'apartment'||Metropolitan dialects including Egyptian Arabic. Corresponds to /q/ in Literary Arabic.|
|Chechen||? / qo'||[qo?]||'three'|
|Chinese||Cantonese||?/oi3||[:i?]||'love'||See Cantonese phonology.|
|Czech||pou?ívat||[po?u?i:vat]||'to use'||See Czech phonology.|
|Dahalo||ma'a||[ma?a]||'water'||see Dahalo phonology|
|Danish||hånd||['hn?]||'hand'||One of the possible realizations of stød. Depending on the dialect and style of speech, it can be instead realized as laryngealisation of the preceding sound. See Danish phonology.|
|Dutch||beamen||[b'a:m?(n)]||'to confirm'||See Dutch phonology.|
|Australian||cat||[k?æ?(t)]||'cat'||Allophone of /t/. See glottalization and English phonology.|
|RP and GA||button||'button'|
|Esperanto||scii||['st?si.?i]||'to know'||See Esperanto phonology.|
|Finnish||linja-auto||['linj?uto]||'bus'||See Finnish phonology.|
|German||Northern||Beamter||[b?'?amt?]||'civil servant'||See Standard German phonology.|
|Guaraní||avañe'?||[ãã']||'Guaraní'||Occurs only between vowels.|
|Hawaiian||ʻeleʻele||['l?'l?]||'black'||See Hawaiian phonology.|
|Hebrew||?||[mamar]||'article'||Often elided in casual speech. See Modern Hebrew phonology.|
|Icelandic||en||[n]||'but'||Only used according to emphasis, never occurring in minimal pairs.|
|Iloko||nalab-ay||[nalab'?aj]||'bland tasting'||Hyphen when occurring within the word.|
|Indonesian||bakso||[?bä?'so]||'meatball'||Allophone of /k/ or /?/ in the syllable coda.|
|Javanese||anak||[änä?]||'child'||Allophone of /k/ in morpheme-final position.|
|Korean||?||[?il]||'one'||In free variation with no glottal stop. Occurs only in initial position of a word.|
|Malay||tidak||['tidä?]||'no'||Allophone of final /k/ in the syllable coda, pronounced before consonants or at end of word.|
|Mutsun||tawka'li||[tawka?li]||'black gooseberry'||Ribes divaricatum|
|Nahuatl||tahtli||[ta?t?i]||'father'||Often left unwritten.|
|Nez Perce||yáaka?||['ja:ka?]||'black bear'|
|Nheengatu||ai||[a'?i]||'sloth'||Transcription (or absence thereof) varies.|
|Persian||?||[ma?ni]||'meaning'||See Persian phonology.|
|Portuguese||Vernacular Brazilian||ê-ê||[e?'?e:]||'yeah right'||Marginal sound. Does not occur after or before a consonant. In Brazilian casual speech, there is at least one [?]-vowel length-pitch accent minimal pair (triply unusual, the ideophones short ih vs. long ih). See Portuguese phonology.|
|Some speakers||à aula||['a '?awl?]||'to the class'|
|Sardinian||Some dialects of Barbagia||unu pacu||['u:nu pa?u]||'a little'||Intervocalic allophone of /n, k, l/.|
|Some dialects of Sarrabus||sa luna||[sa ?u?a]||'the moon'|
|Serbo-Croatian||? ? / i onda||[iô?n?d?a?]||'and then'||Optionally inserted between vowels across word boundaries. See Serbo-Croatian phonology|
|Spanish||Nicaraguan||más alto||['ma '?al?t?o?]||'higher'||Marginal sound or allophone of /s/ between vowels in different words. Does not occur after or before a consonant. See Spanish phonology.|
|Yucateco||cuatro años||['kwat?o? '?ã?o?s]||'four years'|
|Tagalog||oo||[o?o]||'yes'||See Tagalog phonology.|
|Thai||[?a:]||'uncle/aunt' (father's younger sibling)|
|Vietnamese||oi||[j?]||'sultry'||In free variation with no glottal stop. See Vietnamese phonology.|
|Võro||piniq||['pin?i?]||'dogs'||"q" is Võro plural marker (maa, kala, "land", "fish"; maaq, kalaq, "lands", "fishes").|
|Wagiman||jamh||[tm?]||'to eat' (perf.)|