Back in 2005, I wrote up my study of US and UK spelling differences and published a comprehensive* list. Over the next 8 years, it’s by far the article that I’ve had the most feedback on, most of it noting one or two spellings that I missed. I eventually stopped updating the page, but since I continue to get notes, I’ve decided to do a full update and present this as a central repository for the list in an easier-to-read format.
* It would be impractical to try to offer a truly comprehensive list of any words like this, since you can make a couple of different verb forms out of almost any noun, a couple of different nouns out of nearly any verb, etc. So capital can become capitalize and capitalizes, then capitalization and capitalizing, then capitalizations and capitalizings, and even capitalizationing and capitalizationings. And then you can negate or reverse them: decapitalizationing, recapitalizationing, pseudocapitalizationing, etc. This is why any estimates of total number of words in the language or someone’s vocabulary are fairly meaningless.
I count about 1,800 of the little buggers, roots and derivatives included. That’s a lot of differences, but they break down into ten or eleven types:
- -ise vs -ize
- -ll- vs -l-
- (final -l vs final -ll)
- -ae- vs -e-
- -oe- vs -e-
- -our vs -or
- -tre vs -ter
- -gramme vs -gram
- -logue vs -log
- -ence vs -ense
Why list all 1800 differences? Why not just list root words? Sometimes, the difference lies not in the root (chanel, travel) but in the derivative (chanelling/chaneling, travelling/traveling). Or the difference is in the root (glamour/glamor, enthral/enthrall) but disappears in the derivative (glamorous, enthralling).
Also, the purpose of this list is to be a comprehensive collection that may come in useful if you find you need to “Americanize” your British spelling or “Briticise” your American spelling. A root-only list would not only require more work for me (to cull the derivatives) but, for anyone wanting to actually use the list programmatically (in a Word substitution macro, for example) more work to recreate all the derivatives.
In each sub-headings below, the UK spelling is first, then the US spelling.
-ise vs -ize
This includes words like agonise and terrorise as well as oddballs analyse and paralyse. This is the big dog. It covers close to 900 words. However, there are plenty of words that Americans spell -ise that don’t have the meaning “to make or create X,” including surprise, advertise, improvise. And then there’s televise, which does mean “to make into a television broadcast.”
Note that the origin of the -ise and -ize endings are different.
-ll- vs -l-
This is a strange category that actually encompasses -ller, -lling, -lled, and related constructions. It’s big—about 140 words—but very inconsistent. UK spellings like funnelled, controller, and jewellery fit the category but don’t look too odd to Americans because of enrolled, fulfilled, and similar words. Panel follows this form with paneled in the US and panelled in the UK. However, it’s just the opposite for empanel. It becomes empanelled in the US and empaneled in the UK! And, as any frequent flier knows, cancelled and canceled exist pretty much equally in US English.
(Final -l vs final -ll)
Call it a small sub-category or a call it a communist plot, words that actually end in L follow a contrary rule to the one above. Words that end in -ll in the US end in -l in the UK. So Yanks write appall, instill, and enroll, while Brits write appal, instil, and enrol. Both write awful, harmful, stressful, etc. despite the obvious connection to full.
Before you say, “Aha! Americans double the L on the end when it’s a two-syllable word with the accent on the second syllable!” feast your eyes on cartel and canal—but those are nouns, silly!—and excel, propel, and repel—well, okay, those are verbs. Brits write fulfil, but also refill. To quote the great English poet Taupin:
It’s sad. So sad. It’s a sad, sad situation. And it’s growing more and more absurd.
-ae- vs -e-
Aeon, haemorrhage, and paedophile look funny to Americans, who are used to seeing eon, hemorrhage, and pedophile. They seem old-fashioned or even ancient. They come from Latin, of course, and the vowel usually makes the long E sound (altho Americans often let it drop to short E). About 70 words fall into this category. Even so, Americans write aerodynamics (and other aero- words) and sometimes archaeology and aesthetic instead of archeology and esthetic—even tho you won’t see one writing anaesthetic like the Brits.
-oe- vs -e-
Similar to -ae-, -oe- words like foetal and diarrhoea look strange and foreign to Americans. The -oe- nearly always makes the long E sound (manoeuvre is an exception). This category includes about 25 words. On the other hand, Americans generally write subpoena, amoeba, and onomatopoeia, even tho valid non-oe- constructions exist (that is, they are valid but not preferred).
-our vs -or
The “cosmetic U,” as linguists call it, comes from Old French and wore out its welcome early. Americans have done without it in words like colour and favour for a long time, but a few examples linger on: Americans write glamour. About 150 words fit in this category.
We might expand this category slightly to include mould, moustache, and similar words.
-tre vs -ter
Some Americans love to affect the Anglo-French -re spellings for centre and theatre, yet wouldn’t be caught dead writing kilometre or lustre. This is probably the best-known difference, at least among Americans, yet only about 40 words fall into the category, most of which are derivatives of metre and litre.
We might broaden this category slightly to include calibre, manoeuvre, sabre, sepulchre, sombre, and their derivatives.
-gramme vs -gram
This includes programme and kilogramme. Programme happens to be changing to the American spelling, largely influenced by the term computer program and other -gram words (about 17). Aside from it and aerogramme, only metric system words fit this category. The total is about 16 words.
-logue vs -log
The Brits still stick to the old spellings of catalogue and monologue. These are considered acceptable to Americans, but a bit dated. Americans have a tough time deciding to write travelog, tho, or cataloging rather than cataloguing. Only about 15 words fit in this category.
-ence vs -ense
An even smaller group than the previous, the -ence root words number just nine: defence, licence, offence and their ilk. There are nearly 200 valid -ence words in US English. Why these few would be singled out for change is unclear. Fewer than 20 -ense words are found in both types of English (sense, dense, immense, etc.).
In UK English, license is the verb while licence is the noun, whereas in US English, license does double duty. Interestingly, this is somewhat similar to the difference between advice and advise, but these are pronounced differently.
A number of other spelling differences don’t fall into any of the other categories.
- aluminium vs aluminum (this is due to historical happenstance)
- behoves vs behooves
- bevvy vs bevy
- cheque vs check
- cypher vs cipher
- connexion vs connection (connexion is dying out in the UK)
- draught vs draft
- gaol vs jail (gaol is largely converted to the US spelling, even in England)
- omelette vs omelet (you’ll see both in the US)
- plough vs plow
- tyre vs tire
- yoghurt (and even yoghourt) vs yogurt
- judgement vs judgment (you’ll see both in the UK)
Americans want to put the E in there, but their spell-checkers tell them not to. Brits often do put an E in there, altho I’m told this is not necessarily standard UK English either.
- practise (verb) and practice (noun) vs practice
In the course of studying the differences between US and UK spelling, I’ve come across a few peculiarities of interest.
- Both US and UK prefer glamour (but US accepts the non-preferred glamor). But both also prefer glamorous to glamourous.
- Both US and UK insist on Caesar, but US prefers cesarean to caesarean.
- The use of disc vs disk is hopelessly confused. Both insist on disc jockey and disc brakes. But both also insist on floppy disk and hard disk. In general, UK prefers disc and US prefers disk, but the spelling of the expanded form of CD depends mainly on whether you are talking about music (compact disc) or data (compact disk).
- US insists on disheveled, initialed, and similar single-L spellings while UK insists on dishevelled, initialled, etc.
- Full is the only word in US or UK English that ends in -full. Related words are always spelled with a single L: handful, teaspoonful, artful, successful, etc. (And, as noted above, US insists on fulfill while UK insists on fulfil.)
- Smidgen, smidgeon, and smidgin are all valid variants in US and UK English (with smidgen being preferred in both).
- “Fraternal twin” words like dreamt vs dreamed, leapt vs leaped, and speciality vs specialty are treated as entirely different words here, since some are sometimes found in both US and UK English.