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Some words shared by all English speakers are spelled differently by Americans and Britons. Many of these are American "simplification" of the original spellings, often due to Noah Webster. In some cases, the American versions have found their way across the Atlantic and become common British usage as well, for example program (in the computing sense).
- Words ending in -our: British colour, favour, flavour, honour, humour, labour, savour, etc.; American color, favor, flavor, honor, etc. Also derivatives and inflected forms: British favourite, savoury; American favorite, savory.
- Words ending in -re: British centre, fibre, metre, theatre (showing an influence from French); American center, fiber, meter, theater. Britons use meter for a measuring device and metre for the unit of measure. The British forms are recognizable by Americans and occasionally found in American texts, though their usage may be considered an affectation.
- Verb past tenses with -t: British dreamt, leapt, learnt, spelt; American dreamed, leaped, learned, spelled. As with the "tre" words, these are occasionally found in American texts. The forms with -ed are also common in British English. (The two-syllable form learned is still used to mean "educated" in British English.)
- Other verb past tense forms: British fitted, forecasted, knitted, lighted, wedded; American fit, forecast, knit, lit, wed. However, lit and forecast are also the usual forms in British English. Also, the American participle gotten is never used in British English, which uses got (as do some Americans). British usage retains the forgotten form, though.
- Greek-derived words with ae and oe: British aeroplane, aesthetic, amoeba, anaesthesia, archaeology, diarrhoea, encyclopaedia, foetus, gynaecology, mediaeval; American airplane, esthetic, ameba, anesthesia, archeology, diarrhea, encyclopedia, fetus, gynecology, medieval. British manoeuvre seems to be a special case: its oe was not derived from Greek, but was apparently changed to maneuver in American English on the mistaken belief that it was. Some of the British forms are common in American usage as well, particularly aesthetic and amoeba.
- Words ending in -gue: British analogue, catalogue, dialogue; American analog, catalog, dialog. The -gue forms are still common in some American usages such as demagogue.
- Words ending in -ise: British colonise, harmonise, realise; American colonize, harmonize, realize. However, it is not really true that -ise is standard in British English: both the Oxford English Dictionary and Fowler's Modern English Usage prefer -ize. Derivatives and inflected forms: British realisation; American realization. Also: British analyse; American analyze.
- Words ending in -xion: British connexion, inflexion, reflexion; American connection, inflection, reflection. But the forms in -ction are the usual ones in British English too.
- Nouns of direction with -wards: British forwards, upwards, afterwards, etc.; American forward, upward, afterward. However, there is no real distinction here, as both forms are used in both dialects, except that afterward is rare in British English.
- British English generally doubles final -l when adding postfixes that begin with a vowel, where Amercian English doubles it only on stressed syllables. British counsellor, equalling, modelling, quarrelled, signalling, travelled; American counselor, equaling, modeling, quarreled, signaling, traveled. But compelled, excelling, propelled, rebelling in both. Britons sometimes use a single l before postfixes beginning with a consonant where Americans use a double: British enrolment, fulfilment, skilful; American enrollment, fulfillment, skillful.
- British English often keeps silent e when adding postfixes where American English doesn't. British ageing, judgement, routeing; American aging, judgment, routing. Arguement is found in some places (like where?), though the form argument is universal in British English.
- Nouns ending in -ce with -se verb forms: American English retains the noun/verb distinction in advice / advise (pronouncing them differently), but has lost the same distinction with licence / license and practice / practise that British English retains. American English uses "practice" exclusively for both meanings, and "license" for both meanings (although "licence" is an accepted variant spelling). Also, British defence, offence, pretence; American defense, offense, pretense.
- Miscellaneous: British aluminium, cheque, draught, gaol, jewellery, kerb, mould, plough, pyjamas, programme, speciality, sulphur, tyre; American aluminum, check, draft, jail, jewelry, curb, mold, plow, pajamas, program, specialty, sulfur, tire. The word curb is used in British for the verb meaning "to lessen", but the edge of a roadway is always a kerb. British English uses both draught and draft, depending on the sense, and uses jail more often than gaol. The form program is normal in British English when referring to a computer program, but for other uses programme is usual. British use storey for a level of a building and story for a tale; Americans use story for both. Americans use vise for the tool and vice for the sin, while British use vice for both.
- Collective nouns: Nouns like "team" and "company" that describe multiple people are often used with the plural form of a verb in British English, and with the singular form in American. British "the team are concerned"; American "the team is concerned".
- Differences in which nouns are the same in both their plural and singular forms, such as the word "sheep". In American English "shrimp" is such a word but with British English the plural of "shrimp" is "shrimps". ("Shrimps" is occasionally heard in the southern U.S., but is otherwise rare).
- American newspapers tend to write "U.S.", "U.N.", etc., while most British newspapers will write "US", "UN", etc.
The differences most likely to create confusion are in the use of different words for concepts. Most of these are for modern concepts where new words were coined independently, or else the terms are slang or vulgar. Regional variations even within the US or the UK can create the same problems.
It should also be noted that most American words can be freely interchanged with their British versions within the United Kingdom without leading to confusion. It tends to be only when the situation is reversed that problems occur. However, there are some exceptions, such as dumpster and stroller (in the sense of pushchair) which are unlikely to be understood by most speakers of British English.
Words only used in British English
aerial antenna arse ass (buttocks) barrister lawyer (distinction only in British law) bollocks balls (testicles) (interchangeable in British English) bloody damn (e.g., This bloody car won't start.) bonnet (of a car) hood boot (of a car) trunk candy floss cotton candy concession discount crisps chips (e.g., potato or corn) current account checking account engaged tone busy signal fairy cake cupcake indicator turn signal laundrette laundromat lorry truck (interchangeable in British English) maths math MD (managing director) CEO (Chief Executive Officer) mobile (phone) cell phone nappy diaper paraffin kerosene petrol gasoline pram baby carriage pudding dessert (interchangeable in British English) randy horny (interchangeable in British English) ring someone call someone (interchangeable in British English) settee couch (interchangeable in British English) shag fuck (interchangeable in British English) (shag is a kind of carpet and a dance in American English) snogging kissing / "making out" spanner wrench solicitor lawyer (distinction only in British law) sticking plaster Band-Aid
Words only used in American English
Speakers of British English are generally aware of the American English term, but would not generally use it.
ass arse busy signal engaged tone checking account current account cookie biscuit cotton candy candy floss cupcake fairy cake diner cafe dumpster skip french fries chips gasoline petrol math maths stroller pram turn signal indicator
Words which have one meaning in British English and another in American English
Word American equivalent of British equivalent of exclusively British exclusively American meaning meaning bum butt (buttocks) hobo, homeless person cafe diner French cafe chemist pharmacist, pharmacy chips french fries crisps biscuit cracker or cookie bonnet hood (of a car) boot trunk (of a car) dummy pacifier fag cigarette queer fanny pussy (vagina) bum (not obscene) flat apartment lift elevator lounge living room pavement sidewalk the road surface pissed drunk angry rubber eraser rubbish garbage / trash silencer muffler skip dumpster tap faucet torch flashlight tube subway underground subway valve tube, or vacuum tube
The name of the letter Z is pronounced zed in British English as opposed to zee in American English, though the words are rarely spelled out in either. Some greek letters, such as theta and beta, are also pronounced differently.