Every student of the English language, as well as every native English speaker around the world, knows that some words can be spelled in different ways and worries about which spelling to use. They may or may not be aware that this is largely due to variance between the official dictionaries of the countries of the United Kingdom and the United States.
The following is an attempt at a complete list of UK English words that have different spellings in the United States due to historical changes made since its independence, in an attempt to make the language look a little more like it sounds. Not a great many changes have been made overall. The French -re word endings have been reordered to American -er because this is how they are spoken, and similarly the -ou in candour and honour, and comparable words, have been reduced to the -o alone that is sounded. You will see that words derived from the Greek such as ‘aeon’ have been simplified to ‘eon’ for ease of spelling and reading, and a great many words ending in -ise have simply been changed to -ize in the American to reflect how it is indeed pronounced phonetically.
For more on pronunciation and the phonetic alphabet, please see this post.
Not all inflexions of base root words have been given, only token examples; it speaks for itself that ‘acclimatisation’, ‘acclimatise’, ‘acclimatised’, ‘acclimatises’ and ‘acclimatising’ all are spelt with an ‘s’ in their UK English incarnation and a ‘z’ in American English. Likewise, for example, ‘cancellation’, ‘cancellations’, ‘cancelled’ and ‘cancelling’ all retain a double ‘l’ in British English, and retain the single ‘l’ in US English. Do note that some words have changed spellings in more than just one place; that is two or more letters are spelled differently within one word.
A
accessorise = accessorize
acclimatise = acclimatize
accoutrements = accouterments
aeon = eon
aerogramme = aerogram
aeroplane = airplane
aesthete = esthete
aesthetic = esthetic
aetiology = etiology
ageing = aging
aggrandisement = aggrandizement
agonise = agonize
almanack = almanac
aluminium = aluminum
amortisable = amortizable
amphitheatre = amphitheater
anaemia = anemia
anaesthesia = anesthesia
anaesthetise = anesthetize
analogue = analog
analyse = analyze
anglicise = anglicize
annualise = annualize
antagonise = antagonize
apologise = apologize
appal = appall
appetiser = appetizer
arbour = arbor
archaeological =
ardour = ardor
armour = armor
artefact = artifact
authorise = authorize
axe = ax
B
backpedalling = backpedaling
bannister = banister
baptise = baptize
bastardise = bastardize
battle-axe = battleax
baulk = balk
bedevilled = bedeviled
behaviour = behavior
behove = behoove
bejewelled = bejeweled
belabour = belabor
bevelled =beveled
bevvy = bevy
bingeing = binging
bougainvillaea = bougainvillea
bowdlerise = bowdlerize
breathalyse = breathalyze
brutalise = brutalize
buses = busses
C
caesarean = cesarean
calibre = caliber
calliper = caliper
callisthenics = calisthenics
canalise = canalize
cancellation = cancelation
cancelled = canceled
candour = candor
cannibalise = cannibalize
canonise = canonize
capitalise = capitalize
caramelise = caramelize
carbonise = carbonize
carolling = caroling
catalogue = catalog
catalyse = catalyze
categorise = categorize
cauterise =cauterize
cavilling = caviling
centigramme = centigram
centilitre = centiliter
centimetre = centimeter
centralise = centralize
centre = center
centrefold = centerfold
centrepiece = centerpiece
channelling = chaneling
characterise = characterize
cheque = check
chequebook =checkbook
chequered = checkered
chilli = chili
chimaera = chimera
chiselled = chiseled
circularise = circularize
civilise = civilize
clamour = clamor
clangour = clangor
clarinettist = clarinetist
collectivise = collectivize
colonise = colonize
colour = color
colourant = colorant
colourful = colorful
colourise = colorize
colourless = colorless
commercialise = commercialize
computerise = computerize
conceptualise = conceptualize
connexion = connection
contextualise = contextualize
cosier = cozier
cosy = cozy
counsellor = counselor
counselling =counseling
criminalise = criminalize
criticise = criticize
cruellest = cruelest
crystallisation = crystalization
cudgelling = cudgeling
customise = customize
cypher = cipher
D
decentralisation = decentralization
decriminalise = decriminalize
defence = defense
defenceless = defenseless
demeanour = demeanor
demilitarisation = demilitarization
demobilise = demobilze
democratise = democratize
demonise = demonize
demoralise = demoralize
denationalise = denationalize
deodorise = deodorize
depersonalise = depersonalize
deputise = deputize
desensitisation = desensitization
destabilise = destabilze
dialling = dialing
dialogue = dialog
diarrhoea = diarrhea
digitise = digitize
disc = disk
discolour = discolor
disembowelling = disemboweling
disfavour = disfavor
dishevelled = disheveled
dishonour = dishonor
disorganisation = disorganization
distil = distill
dramatising = dramatizing
draught = draft
draughtsman = draftsman
drivelling = driveling
duelled = dueled
E
economise = economize
edoema = edema
editorialise = editorialize
empathise = empathize
emphasise = emphasize
enamelled = enameled
enamoured = enamored
encyclopaedia = encyclopedia
endeavour = endeavor
energise = energize
enrol = enroll
enthral = enthrall
enquire = inquire
epaulette = epaulet
epicentre = epicenter
epilogue = epilog
epitomise = epitomize
equalisation = equalization
eulogise = eulogize
evangelise = evangelize
exorcise = exorcize
extemporisation = extemporization
exstemalisation = extemalization
externalise = externalize
F
factorise = factorize
faecal = fecal
faeces = feces
familiarisation = familiarization
fantasise = fantasize
favour = favor
favourable = favorable
favourite = favorite
feminise = feminize
fertilise = fertilize
fervour = fervor
fibre = fiber
fictionalise = fictionalize
fillet = filet
finalise = finalize
flautist = flutist
flavour = flavor
foetal = fetal
foetid = fetid
foetus = fetus
formalise = formalize
fossilise = fossilize
fraternise = fraternize
fulfil = fulfill
fulfilment = fulfillment
funnelling = funneling
G
galvanise = galvanize
gambolling = gamboling
gaol = jail
gases = gasses
gauge = gage
generalise = generalize
ghettoise = ghettoize
glamorise = glamorize
glamour = glamor
globalise = globalize
glueing = gluing
goitre = goiter
gonorrhoea = gonorrhea
gramme = gram
gravelled = graveled
grey = gray
grovelled = groveled
gruelling = grueling
gryphon = griffon
gynaecological = gynecological
H
haematological = hematological
haemoglobin = hemoglobin
haemorrhage = hemorrhage
harbour = harbor
harmonise = harmonize
homoeopathy = homeopathy
homogenised = homogenized
honour = honor
hospitalise = hospitalize
humanise = humanize
humour = humor
hybridise = hybridize
hypnotise = hypnotize
hypothesise = hypothesize
I
idealise = idealize
idolise = idolize
immobilise = immobilize
immortalise = immortalize
immunise = immunize
impanelling = impaneling
imperilled = imperiled
individualise = individualize
industrialise = industrialize
inflexion = inflection
initialise = initialize
initialled = initialed
instal = install
instalment = installment
instil = instill
institutionalise = institutionalize
intellectualise = intellectualize
internalise = internalize
internationalise = internationalize
ionise = ionize
italicise = italicize
itemise = itemize
J
jeopardise = jeopardize
jewelled = jeweled
jewellery = jewelry
judgement = judgment
K
kilogramme = kilogram
kilometre = kilometer
L
labelled = labeled
labour = labor
lacklustre = lackluster
legalise = legalize
legitimise = legitimize
leukaemia = leukemia
leveller = leveler
libellous = libelous
liberalise = liberalize
*licence = license
licencing = licensing
likeable = likable
lionise = lionize
liquidise = liquidize
litre = liter
localise = localize
lustre = luster
M
magnetise = magnetize
manoeuvre = maneuver
marginalise = marginalize
marshalling = marshaling
marvelled = marveled
marvellously = marvelously
materialise = materialize
maximise = maximize
meagre = meager
mechanise = mechanize
mediaeval = medieval
memorialise = memorialize
memorise = memorize
mesmerise = mesmerize
metabolise = metabolize
*metre = meter
militarise = militarize
milligramme = milligram
millilitre = milliliter
miniaturise = miniaturize
minibuses = minibusses
minimise = minimize
misbehaviour = misbehavior
misdemeanour = misdemeanor
misspelt = misspelled
mitre = miter
mobilise = mobilize
modelled = modeled
modernise = modernize
moisturise = moisturize
monologue = monolog
monopolise = monopolize
moralise = moralize
motorise = motorize
mould = mold
moult = molt
moustache = mustache
multicoloured = multicolored
mum = mom
N
nationalise = nationalize
naturalise = naturalize
neighbour = neighbor
neighbourhood = neighborhood
neutralise = neutralize
normalise = normalize
O
odour = odor
oesophagus = esophagus
oestrogen = estrogen
offence = offense
omelette = omelet
optimise = optimize
organise = organize
orthopaedic = orthopedic
ostracise = ostracize
outmanoeuvre = out maneuver
overemphasise = overemphasize
oxidise = oxidize
P
paederast = pederast
paediatrician = pediatrician
palaeolithic = paleolithic
palaeontologist = paleontologist
panelled = paneled
paralyse = paralyze
parcelled = parceled
parlour = parlor
particularise = particularize
passivise = passivize
pasteurise = pasteurize
patronise = patronize
pedalling = pedaling
pedestrianisation = pedestrianization
penalise = penalize
pencilling = penciling
personalise = personalize
pharmacopoeia = pharmacopeia
philosophise = philosophize
phoney = phony
plagiarise = plagiarze
plough = plow
polarise = polarize
politicise = politicize
popularise = popularize
*practise = practice
practising = practicing
praesidium = presidium
pressurise = pressurize
pretence = pretense
primaeval = primeval
prioritise = prioritize
privatise = privatize
professionalise = professionalize
programme = program
prologue = prolog
propagandise = propagandize
proselytise = proselytize
psychoanalyse = pyschoanalyze
publicise = publicize
pulverise = pulverize
pummelling = pummeling
pyjamas = pajamas
pzazz = pizzazz
Q
quarrelling = quarreling
R
radicalise = radicalize
rancour = rancor
randomise = randomize
rationalise = rationalize
ravelling = raveling
realise = realize
recognise = recognize
reconnoitre = reconnoiter
refuelled = refueled
regularise = regularize
remodelled = remodeled
remould = remold
reorganise = reorganize
revellers = revelers
revitalise = revitalize
revolutionise = revolutionize
rhapsodise = rhapsodize
rigour = rigor
ritualise = ritualize
rivalled = rivaled
romanticise = romanticize
rumour = rumor
S
sabre = saber
saltpetre = saltpeter
sanitise = sanitize
satirise = satirize
saviour = savior
savour = savor
scandalise = scandalize
sceptic = skeptic
sceptical = skeptical
sceptre = scepter
scrutinise = scrutinize
secularise = secularize
sensationalise = sensationalize
sensitised = sensitized
sentimentalise = sentimentalize
sepulchre = sepulcher
serialise = serialize
sermonise = sermonize
sheikh = sheik
shovelled = shoveled
shrivelled = shriveled
signalise = signalize
signalling = signaling
smoulder = smolder
snivelled = sniveled
snorkelled = snorkeled
snowplough = snowplow
socialise = socialize
solemnise = solemnize
sombre = somber
specialise = specialize
spectre = specter
spiralling = spiraling
splendour = splendor
squirrelling = squirreling
stabilise = stabilize
standardise = standardize
stencilling = stenciling
sterilise = sterilze
stigmatise = stigmatize
storey = story
subsidised = subsidized
succour = succor
sulphate = sulfate
sulphide = sulfide
sulphur = sulfur
summarise = summarize
swivelling = swiveling
symbolise = symbolize
sympathise = sympathize
synchronise = synchonize
synthesise = synthesize
syphon = siphon
systemise = systemize
T
tantalise = tantalize
tasselled = tasseled
technicolour = technicolor
temporise = temporize
tenderise = tenderize
terrorise = terrorize
theatre = theater
theorise = theorize
tonne = ton
towelling = toweling
toxaemia = toxemia
tranquillise = tranquilize
tranquilliser = tranquilizer
transistorise = transistorize
traumatise = traumatize
traveller = traveler
travelogue = travelog
trialling = trialing
tricolour = tricolor
trivialise = trivialize
tumour = tumor
tunnelling = tunneling
tyrannise = tyrannize
tyre = tire
U
unauthorised = unauthorized
uncivilised = uncivilized
underutilised = underutilized
unequalled = unequaled
unfavourable = unfavorable
unionise = unionize
unorganised = unorganized
unravelled = unraveled
unrecognised = unrecognized
unrivalled = unrivaled
unsavoury = unsavory
untrammelled = untrameled
urbanise = urbanize
utilise = utilize
V
valour = valor
vandalise = vandalize
vaporise = vaporize
vapour = vapor
verbalise = verbalize
victimise = victimize
vigour = vigor
visualise = visualize
vocalise = vocalize
vulcanise = vulcanize
vulgarise = vulgarize
W
waggon = wagon
watercolour = watercolor
weaselled = weaseled
westernisation = westernization
womanise = womanize
woollen = woolen
worshipped = worshiped
Y
yodelling = yodeling
yoghurt = yogurt
Please also visit this post on different UK and US words.
Further notes to eliminate confusion
‘Licence’ as a noun in UK English is spelt ‘license’ in the US. The word spelt ‘license’ in the UK is the verb form of the word, which is also spelt ‘license’ in the US.
‘Metre’ is a unit of measurement in UK English, and this is spelt as ‘meter’ in the US. There is also, however, a word spelt ‘meter’ in the UK, which is a different word for a device to measure an amount of something used, such as an electricity meter. This word is also spelt ‘meter’ in the US.
‘Practise’ as a verb in UK English is spelt ‘practice’ in the US. The word spelt ‘practice’ in the UK is the noun form of the word, which is also spelt as ‘practice’ in the US.
‘Tyre’ in the UK is spelt ‘tire’ in the US, and refers to the black rubber ring around the wheel on a vehicle. However, there is also a word spelt ‘tire’ in the UK, which similarly to its US counterpart is a verb meaning to exhaust or to lose energy.
Conclusion
You may think some words are missing from this list – there may well be – but please be aware that not all similar UK English words have changed spellings. ‘Exercise’, for example, has retained its original spelling in the US.
When one looks at how many illogical ancient spellings have been allowed to remain in the dictionary, one can be grateful that not more spellings were changed because, for many people these days, the discrepancies between English’s multiple standards can be a little confusing! However, there are still movements of people on both sides of the Atlantic who do want to change spellings to further simplify them. Furthermore, while there are some British English spellings that are also accepted in the US and vice versa, not all are. The most important thing when writing any piece is to be consistent with one’s spelling and ensure that all the spellings one uses within a particular text use spellings that match and correspond with one’s other choices.
Test yourself
Do add any comments below and please do submit any omissions you may be aware of.
BIBLIOGRAPHY
Bryson, Bill. The Mother Tongue: English and how it got that way (Perennial, 2001)
Cresswell, Julia. Oxford Dictionary of Word Origins, 3rd edn (Oxford University Press, 2021)
Crystal, David. Spell it Out: The Singular Story of English Spelling (Profile Books, 2013)
Dreyer, Benjamin. Dreyer’s English: An Utterly Correct Guide to Clarity and Style (Penguin Random House, 2020)
Hickey, Raymond. Standards of English: Codified Varieties Around the World (Cambridge University Press, 2015)
Huddleston, Rodney, and others. The Cambridge Grammar of the English Language (Cambridge University Press, 2002)
McWhorter, John. The Power of Babel: A Natural History of Language (Harper Perennial, 2003)
Moore, Erin. That’s Not English: Britishisms and What Our English Says About Us (Penguin Random House, 2015)
Quirk, Randolph, and others. A Comprehensive Grammar of the English Language, reprint edn (Pearson, 2011)
New Hart’s Rules: The Handbook of Style for Writers and Editors (Oxford University Press, 2005)