In many parts of North America (about half the United States and nearly all of Canada) /ɑː/ and /ɔː/ sound the same. This is in addition to the father-bother merger, where /ɑː/ and /ɒ/ sound the same. This means that caught /ɔː/ and cot /ɒ/ (also father /ɑː/ and bother /ɒ/) have the same stressed vowel /ɑː/. In this accent /ɔː/ appears only followed by /r/: north, force.
This accent (which is not General American) is so prevalent that it is used in Merriam-Webster's Learner's Dictionary and in Cambridge Dictionaries Online for British English, US label. Note that Cambridge Dictionaries Online list two different American pronunciations, the one in Essential American English doesn't have the merger.
It can be conjectured that the spread of this merger via mass media has made some particular “modern” words to be pronounced with /ɑː/ even in dialects that have /ɔː/. For example "astronaut" pronounced as /ˈæstrəˌnɑːt/ in addition to /ˈæstrəˌnɔːt/.
Other names for this merger (better for those who have it) are "LOT - THOUGHT merger" or "PALM - LOT - THOUGHT merger". There is an area in the United States (in New England) where "lot" and "thought" are merged as [ɒ] but "palm"/"father" is different (as [ɑ]). This means that strictly speaking "LOT - THOUGHT merger" and "PALM - LOT - THOUGHT merger" are different concepts.
The cot-caught merger is present also in Europe, but there the father-bother merger does not appear (similar to the area in New England mentioned above). The rest of this article is about the North American merge.
Comparison of phonemes
|Sample word||Merriam Webster's
British English - US
Essential American English
|Most American Dictionaries
(if they use IPA)
|orange||[ɑr, or]||/ɔr/||/ɔr, ɑr/||/ɔr/||/ɒBrE, ɔːAmE/|
|cloth||[ɑː]||/ɑː/||/ɔ/||/ɔ/||/ɒ*/ or /ɒBrE, ɔːAmE/|
|moral||[or]||/ɔːr/||/ɔr, ɑr/||/ɔːr/||/ɒBrE, ɔːAmE/|
|force||[oɚ]||/ɔːr/||/ɔr/||/ɔr/ and sometimes /oʊr/||/ɔːr/|
|glory||[or]||/ɔːr/||/ɔr/||/ɔr/ and sometimes /oʊr/||/ɔːr/|
Sometimes we mark the CLOTH vowel with an asterisk, as follows:
- *: These words are pronounced with /ɔː/ in General American.
The cot-caught merger generates very few homophones.
- bot (computer program; shortening of robot) - bought; collar - caller; cot - caught; don (put clothes on)/Don (nickname of Donald) - dawn/Dawn; stock - stalk; tot (very young child) - taught;
The PALM - LOT - THOUGHT merger generates even fewer homophones.
Phoneme /ɑː/ in the PALM - LOT - THOUGHT merger
This article is valid in an area in North America where the following words have the same phoneme vowel: "start", "art", "palm", "spa", "lot", "stop", "thought" and "law".
Many people pronounce /ɑː/ and /ɑːr/ with different vowels (e.g. lodge as [lɑdʒ] and large as [lɑːrdʒ]); however since the difference is predictable there is no problem using the same symbol in both cases (e.g. /lɑːdʒ/ and /lɑːrdʒ/).
Some common words which practice the pronunciation of /ɑː/ include the following:
- with "a": father, iguana, llama, piñata, wad, wander, want, wash, wasp, watch, water
- with "al": almost, already, also, alter, always, false, salt
- "al" as /ɑː/: calm, chalk, palm, talk, walk
- with "all": ball, call, fall, hall, mall, small, wall, wallet
- with "ar": are, aren't, arm, art, article, bar, car, charge, dark, department, far, farm, hard, harm, large, market, park, part, party, regard, smart, star, start, warrant, warranty
- with "o": Boston, chocolate, cloth, cost, follow, gone, got, hot, job, long, lost, lot, not, off, offer, office, often, on, possible, probably, problem, process, product, shop, song, strong, stop, top, wrong
- with "oa": abroad, broad
- with "ough": cough, ought, thought
- past tense and past participle: bought, brought, fought, sought, thought
- with "aw": dawn, draw, flaw, hawk, jaw, law, lawn, raw, saw, shawl, thaw, yawn
- with "au": auction, August, Aussie, austerity, Australia, Austria, author, autumn, cause, clause, daughter, fault, launch, pause
- past tense and past participle: caught - taught
- /ɑː/ or /ʌ/: because, what
- heart, knowledge
- bomb - balm; caller - collar; knot - not;
/ɑːr/ or /ɔːr/
- borrow,(*) morrow(*) (shortening of "tomorrow"), sorrow, sorry, tomorrow(*)
According to Wikipedia, the following words are pronounced with /ɑː/ by some speakers and with /ɔː/ by others. Only words marked with (*) have two pronunciations in Merriam-Webster's Learner's Dictionary; the rest have only /or/, equivalent to Teflpedia's /ɔːr/.
- corridor, euphoric, foreign, forest, Florida,(*) historic, horrible, majority, minority, moral, orange,(*) Oregon, origin, porridge, priority, quarantine, quarrel, sorority, warranty, warren, warrior
Anticipated pronunciation difficulties depending on L1
In Latin America American English is taught (the United Kingdom is far away). Spanish speakers tend to pronounce /ɑː/ according to the spelling. They will pronounce "palm" as [pam] and "lot" as *.
- William Labov,The Organization of Dialect Diversity in North America, The o/oh merger [i.e. The /ɑː - ɔː/ merger].
- Wikipedia, Phonological history of English low back vowels § Cot–caught merger. Retrieved 14 April 2016.
- JeffinNYC in Antimoon Forum, "cot" and "caught", page 1, June 22, 2010
- Random House Dictionary in Dictionary.com, astronaut.
- Wikipedia, English-language vowel changes before historic /r/ § Mergers of /ɒr-/ and /ɔːr-/. Retreived 14 May 2015.
- Merriam-Webster's Learner's Dictionary. Note that this dictionary writes /ɑː/ in "palm" and "lot", and it writes /ɑ/ in "safari". Teflpedia always uses /ɑː/.
- Cambridge Dictionaries Online - British English. We don't reference the American English section, because an unmerged accent is reported there.
- Merriam-Webster's Learner's Dictionary.