Lexical sets

The phonetician, John Wells, introduced in his book, Accents of English (1982), the concept of using a single word to refer to the pronunciation of a particular group of English words. He calls these word-groups lexical sets and uses a key word, such as BATH to identify them. The BATH vowel refers to the pronunciation of the vowel in the word bath and other words that share that same vowel, such as laugh, ask and dance. Other important lexical sets include the STRUT vowel which occurs in words such as cup, mother, blood and young; the GOAT vowel in words such as soap, grow, rose and old and the NURSE vowel in words such as bird, work, herd, church and earn.

Sound change

Changes in pronunciation — phonological change — come in a variety of forms. Some changes merely affect the way an individual word is pronounced. Older speakers across the UK tend to stress the first syllable in the word controversy, for instance, while younger speakers increasingly place the main stress on the second syllable, controversy. In other cases, the pronunciation of a particular vowel sound changes gradually across successive generations and thus has an impact on a large group of words. A change in pronunciation might initially take place only in one particular geographic location and remain local. Or it may over time spread nationally and thus affect all varieties of English.

Introducing the TRAP~BATH split

The vowel used by speakers for words in the TRAP set, such as back, dash, glad, hand, lamp and arrow and words in the BATH set, such as glass, dance and after is thought to have changed very little from the time of the Anglo-Saxon invasions until the 1600s. Up until that point all speakers in England would have used a short vowel — probably not identical to the one most of us use in the TRAP set nowadays, but pretty similar. Both groups of words would have belonged to a single set, so that speakers everywhere would have used an identical vowel in the words cat and cast. We can call this sound ‘a'.

Fashionable pronunciation

From the 1600s onwards, however, it became fashionable in and around London to lengthen the vowel sound in a small number of words where the <a> precedes the consonant sounds <s>, <f> and <th>. Thus in seventeenth century London pat would have been pronounced with the short ‘a' vowel, but path and other similar words would have contained a slightly lengthened version of the same vowel. We can describe this sound as ‘aa’. At a later date, however, speakers in London and the Home Counties started to adopt a completely different long vowel making this new pronunciation distinction even clearer. They retained the original short vowel for words such as rat, but began to use a vowel rather like the sound we are asked to produce when a doctor examines our throat in words such as raft. This vowel sound we can characterise as ‘ah'.

Trap versus bath

Linguists refer to these successive sound changes as the TRAP~BATH split. A significant number of words within the original TRAP set began to be pronounced sufficiently differently by enough people to justify treating the words separately. This set in motion a chain of events that we can observe in a number of ways. We can look at the impact on the language itself and we can trace the impact geographically and socially.

Impact of the TRAP~BATH split on the English Language

For speakers who adopted this new pronunciation and subsequent generations of speakers, the initial sound change gradually spread through the set of English words where <a> precedes the consonant sounds <s>, <f> and <th> - such as class, grasp, ask, mast, staff, craft and bath. At a later date this new pronunciation was extended to include other words where the <a> sound precedes <n> or <m> plus another consonant - such as grant, chance, sample and command. At no point (yet) has either of the two sound changes affected all possible words for all speakers in England, although for RP speakers and those in the south of England, ‘ah’ is now used for the vast majority of words in the BATH set. However, there are still a number of words where pronunciation varies from speaker to speaker, such as photograph, transport, plastic and circumstance.

The table below shows how far the new pronunciation has spread within all the words that might potentially belong in the BATH set

  • The second column lists the words still pronounced with ‘a’ by all speakers in England.
  • The third column contains those words pronounced with ‘ah’ in the south of England and by RP speakers, but with ‘a’ in the north.
  • The right-hand column identifies a number of grey areas, where words could potentially meet the criteria for BATH-broadening, but where in RP and southern English some speakers nonetheless still use an ‘a’ sound. In most cases younger speakers tend to favour the newer pronunciation, ‘ah’, for most of these words - perhaps in a few generations the change will have worked itself even further through the set.
consonant ‘a’ for all speakers ‘ah’ for RP and speakers in the south words that vary from speaker to speaker
<a> + <f>

baffle, café, cafeteria, caffeine, daffodil, faff, gaff, gaffe, Jaffa, naff, raffia, raffle, scaffold, snaffle, taffeta

chaff, giraffe, graph, laugh, staff

Gadaffi, mafia, photograph, riff-raff, telegraph1

<a> + <ft>

BAFTA, faffed, gaffed

aft, after, craft, daft, haft, draft, draught, graft, laughter, raft, rafter, shaft, staffed

<a> + <mpl>

Amanda~Mandy, Andrew~Andy, and, band, brand, brandy, candle, candour, expand, gander, gerrymander, gland, grand, hand, handle, land, mandible, outstanding, panda, pander, prandial, sand, Sandy, scandal, shandy, stand, understand, vandal, withstand

Alexander~Alexandra, chandler, command, Cassandra~Sandra, demand, Flanders, remand, reprimand, Rwanda, slander

<a> + <ns>
(<trans-> also with <nz>)

cancer, cancel, expanse, fancy, manse, romance

advance, answer, askance, chance, chancellor, dance, enhance, trance, France, Frances~Frances, glance, lance, lancet, prance, stance, trance

circumstance, transfer, transform, transgress, transit, transplant, transport etc1

<a> + <nsh> (or <nch>)

expansion, mansion, pancheon, scansion

blanch, branch, ranch, stanchion, tranche

circumstantial, substantial1
<a> + <nt>

ant, banter, cant, canter, decant, Fanta, gantry, mantel, mantra, pant, pantry, rant, romantic, Santa, scant

advantage, chant, enchant, grant, Grant, plant, slant, supplant

<a> + <s>

alas, amass, ass, bass2, chassis, classic, classical, crass, gas, Hamas, glacé, lass, mass, massive, morass, molass, passage, passenger, passive, sassy

brass, class, glass, fasten, grass, pass

<a> + <sk>

Ascot, cardio-vascular, emasculate, gasket, mascot, masculine

ask, bask, basket, Basque, cask, casket, flask, mask, rascal, task

<a> + <sl>

hassle, tassel, vassal


<a> + <sp>


clasp, exasperate, gasp, grasp, hasp, rasp

<a> + <st>

aster, bombast, catastrophe, drastic, enthusiast, gymnast, fantastic, hast, masticate, masturbate, spastic

aghast, alabaster, avast, bastard, blast, cast, castor, contrast, dastardly, disaster, fast, ghastly, last, mast, nasty, past, pastor, pastoral, pasture, pasteurise, vast

elastic, fastidious, pasty, pasta, plastic, rastafarian3 (cf. northern master, plaster)4

<a> + <th>

Cath~Kath, hath, osteopath~psychopath etc., maths

aftermath, bath, lath, path


Afghanistan~Pakistan etc., alto, blasphemy, Cleopatra, contralto, Glasgow, imam, Iran, Iraq, koran, latte, plaque, Saddam, Sudan5

  1. 1 The pronunciation of a number of words ending in <-ance> or <-graph> or beginning with <trans-> varies in southern English and RP between speakers who favour ‘a’ and those who favour ‘ah’.
  2. 2 A fish of the perch family, as in sea-bass.
  3. 3 There are a few polysyllabic words where <a> is followed by <st> where speakers of southern English seem undecided whether to use 'a’ or ‘ah’ - perhaps the most common example is the word plastic.
  4. 4 The words master and plaster are intriguingly pronounced with ‘ah’ (or occasionally ‘aa’) by some speakers in the north - notably on Tyneside and in Yorkshire and Lancashire - although these speakers favour 'a’ in all other instances. This gives rise to the intriguing combination of vowel sounds in words such as plastercast (‘plahstercast’) and elastoplast (‘elastoplahst’) and the Stevie Wonder song Master Blaster becomes ‘mahsterblaster'. ‘Mahster’ and ‘plahster’ do not seem to occur on Merseyside, in Manchester nor in the flat-BATH areas of the Midlands, where pronunciation of the TRAP~BATH sets is consistently ‘a’.
  5. 5 There appear to be several words where RP speakers and southerners are divided between those who favour ‘a’ and those who prefer ‘ah’. Many of these words are foreign in origin and there is, for instance, the set of country names ending in <-stan> where pronunciation varies considerably. Particularly intriguing is the frequent use in the south of England of a seemingly incongruous ‘ah’ in the loan-word latte. There is no precedent for this elsewhere in English - consider words such as chatter, chatty, latter, natter, natty and so on. The word latte is a very recent import, an extremely fashionable item and a high-frequency word, so its unusual pronunciation has spread very quickly. Interestingly, the equally recent and fashionable culinary import, satay, appears to be universally pronounced with 'a’. Satay then, rhymes with latte and indeed with pâté in the north and Midlands but seldom in the south of England.

Impact of the TRAP~BATH split over time and across space

The map below, produced by Clive Upton and John Widdowson is based on data collected in rural England in the 1950s.

Map of UK showing England and wales

If we consider change across time and space, we can see that the most recent form of pronunciation, ‘ah’, had by the 1950s taken firm hold in the South East of England. It had begun to spread in all directions from London and the Home Counties, although there are examples of ‘aa’ to the immediate north and west of London. Nowadays one is increasingly unlikely to hear examples of this ‘intermediate’ sound change, ‘aa’, in the South East of England, although there are some older speakers in rural areas who still use this pronunciation. Thus we can see that at any given time there will be transition areas, where within the same community older speakers favour the older pronunciation, while younger speakers have shifted to the newer form. Over time the older speakers will become increasingly outnumbered until eventually a community is populated only by the next generation of speakers who all share the new pronunciation (unless it too is subject to a new wave of change among its younger speakers).


The pronunciation, ‘aa’, is itself a relatively recent change in pronunciation from the older short vowel, ‘a’, which remains the most common alternative in the north of England and in the Midlands. An isogloss is a line on a map that divides areas where different linguistic forms exist. The BATH Map isogloss that splits England roughly into the ‘flat-BATH’ north and the ‘broad-BATH’ south does not appear to have shifted dramatically in the last fifty years. Click on a location on The BATH Map (Change) to listen to speakers in different parts of the country pronouncing words in this set sixty years ago and compare this with speakers today on The BATH Map (Variation). You will notice that, in most cases, the area where speakers favoured ‘a’ fifty years ago is still intact. However, there does appear to have been a marked change in the areas to the south of that line - the ‘aa’ areas appear to be giving way to pronunciations with ‘ah’. Linguistic boundaries are seldom absolutely clear-cut, so transitional areas exist. In some places some speakers always use ‘a’, while others prefer ‘ah’. Others simply vary between the two - a clear sign that a sound change is in progress within the community. The actual difference between ‘aa’ and ‘ah’ is also not always clearly audible. Some speakers in places like Northamptonshire, Cambridgeshire and East Anglia, for instance, appear to occupy a phonetic ‘half-way house’ between the two extremes - something linguists refer to as fudged pronunciations.

Overseas English

If one looks overseas, most speakers in the USA retain a short vowel for words in both the BATH and TRAP sets. The actual nature of the US vowel is a cross between the <a> sound most speakers in England now use in the word man and the <e> vowel sound in men. We use the phonetic symbol /æ/ to refer to this type of pronunciation. It is possible that it is very close to the original combined TRAP~BATH vowel used before the 1600s in England. English speakers first settled in the USA before the TRAP~BATH split had occurred here, and so in the USA today the pronunciation of those early colonists seems to have been preserved. If we consider Australia and New Zealand, however, speakers from the UK began to settle there after the TRAP~BATH split had begun to take effect here. Not surprisingly, present-day Australians usually use ‘aa’ for words in the BATH set. However, the subsequent sound change to ‘ah’ that occurred in RP and in the south of England has not affected Australian English as it took place here after the original colonial settlements.

Social differentiation in sound change

A sound change like the one that has affected the pronunciation of words in the BATH set can be monitored as it moves through the language and across the country, but it is also possible to track its progress socially. Not everyone north of a certain line pronounces words in this set with ‘a’, as anyone living in the North will know. There are many speakers in the North and the Midlands whose speech is not modelled on local forms. Instead they speak with the regionally non-specific, middle class accent known as RP. Some of these speakers, due to their socio-economic or educational background, pronounce words in the BATH set with ‘ah’. What is particularly intriguing about the BATH vowel, however, is that very many middle class northerners share nearly all the features of RP speakers apart from the use of ‘ah’ for the BATH set. It is only a very small subset of upper middle class northerners who use ‘ah', while large numbers of middle class northerners remain indistinguishable from RP speakers until they use a word like blast or glance with ‘a'. Likewise, many northerners who live in the south of England and have modified their speech as a result, seem particularly resistant to any change in their pronunciation of the BATH vowel. So, this vowel is clearly an extremely strong psychological marker of regional identity for many northerners and Midlanders.

Find Out More

BATH Literature

  • Chambers, J.K. & Trudgill, Peter (1998) Dialectology, 2nd Edn. Cambridge: Cambridge University Press; pp. 104-118.
  • Hughes, Arthur, Trudgill, Peter & Watt, Dominic (2005) English Accents and Dialects: An Introduction to Social and Regional Varieties of English in the British Isles, 4th edn. London: Hodder Arnold; pp. 60-63
  • Kolb, Edward, Glauser, Beat, Elmer, Willy & Stamm, Renate (1979) Atlas of English Sounds. Berlin: Francke Verlag; pp. 183, 187-8, 194-6 & 204
  • Orton, Harold, Sanderson, Stewart & Widdowson, John (1978) The Linguistic Atlas of England. London: Croom Helm; maps ph3 & ph4
  • Upton, Clive & Widdowson, J.D.A. (1996) An Atlas of English Dialects. Oxford: Oxford University Press; pp. 6-7
  • Wells, J.C. (1982) Accents of English I: An Introduction. Cambridge: Cambridge University Press; pp. 133-135 & 232-234