Cot-caught merger

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Revision as of 22:01, 14 May 2015 by Ghoti (talk | contribs) (/ɑː/ in the PALM - LOT - THOUGHT merger; Incomplete version)

In many parts of North America (about half the United States and all of Canada)[1] /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/, cot /ɒ/, father /ɑː/ and bother /ɒ/ have all the same stressed vowel /ɑː/. In this accent /ɔː/ appears only followed by /r/: north, force.

This accent is so prevalent that it is used in Merriam Webster Learner's Dictionary and in Cambridge Dictionaries Online for British English, US label. Note that Cambridge Dictionaries Online list two different American pronunciations, and only the one that is labeled US has the cot-caught merger.

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.

Sample word Merriam Webster's
Learner's Dictionary
Cambridge Dictionaries
British English - US
Cambridge Dictionaries
American English
Most American Dictionaries
(if they use IPA)
palm, father /ɑː/ /ɑː/ /ɑ/ /ɑ/ /ɑː/
start /ɑɚ/ /ɑːr/ /ɑr/ /ɑr/ /ɑːr/
safari /ɑr/ /ɑːr/ /ɑr/ /ɑr/ /ɑːr/
lot /ɑː/ /ɑː/ /ɑ/ /ɑ/ /ɒ/
sorry /ɑr/ /ɔː/ /ɑr, ɔr/ /ɑr/ /ɒr/
borrow /ɑr/ /ɑː/ /ɑr, ɔr/ /ɑr/ /ɒr/
thought /ɑː/ /ɑː/ /ɔ/ /ɔ/ /ɔː/
cloth /ɑː/ /ɑː/ /ɔ/ /ɔ/ */ or /ɒBrE, ɔːAmE/
north /oɚ/ /ɔːr/ /ɔr/ /ɔr/ /ɔːr/
moral /or/ /ɔːr/ /ɔr, ɑr/ /ɔːr/ /ɔːr/
force /oɚ/ /ɔːr/ /ɔr, oʊr/ /ɔr/ and sometimes /oʊr/ /ɔːr/
glory /or/ /ɔːr/ /ɔr, oʊr/ /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;

/ɑː/ in the PALM - LOT - THOUGHT merger

This phonetics article is adapted for an area that includes roughly 50% of North America but is not General American, the accent used in television.


start /stɑːrt/


palm /pɑːm/


lot /lɑːt/



lot /lɑt/

In General American IPA phonetic symbol /ɑː/ corresponds to the vowel sound in words like "start", "art", "palm", "spa", "lot" and "stop".

In Received Pronunciation, the IPA phoneme /ɑː/ corresponds to the vowel sound in words like "start", "art", "bath", "ask", "palm" and "spa".

In most of North America the father-bother merger is in effect.[2] This means that IPA phoneme /ɒ/ sounds exactly like /ɑː/. This is the reason why "lot" and "stop" are mentioned in the first paragraph. Since many of the words with the phoneme /ɑː/ are spelled with the letter ‘o’, this phoneme is sometimes informally called “short o”.

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/).

Common words

Some common words which practice the pronunciation of /ɑː/ include the following:

  • with "a": calm - father - iguana - llama - palm - piñata - wad - wander
  • 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
  • with "o": cost - follow - got - hot - job - lot - not - possible - probably - problem - stop
  • /ɑː/ or /ɔː/: wallet - want - wash - wasp - watch
  • /ɑː/ or /ʌ/: what
  • others: heart

/ɑː/ or /ɔː/

All these words have an /ɒ/ sound in Received Pronunciation. In North America they may sound /ɑː/ or /ɔː/.

  • Boston - chocolate - gone - on - wash

/ɑːr/ or /ɔːr/

  • borrow - Florida - orange - sorrow - sorry - tomorrow

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 *[lot].

See also


  1. William Labov,The Organization of Dialect Diversity in North America, The o/oh merger [i.e. The /ɑː - ɔː/ merger].
  2. Wikipedia, Father-bother merger

External links