I thought it might be fun to compare British v. American English usage. Perhaps Tranter or Charlie can explain how our English cousins came up with some of these!
We'll start with words beginning with "A" or "B" only:
British Words Uncommon in the US
to descend on a rope (US: rappel). From German abseilen
calculating and tracking financial matters (US: accounting).
In the UK accounting is the school subject, but accountancy is the professional qualification.
advertisement (US and UK also: ad, classified ad, commercial).
the author of an agony column – a magazine or newspaper column advising on readers' personal problems. The image presented was originally that of an older woman providing comforting advice and maternal wisdom, hence the name "aunt". Better known to most Americans as a "Dear Abby" column or advice column. Similarly, agony uncle.
aggressive or confrontational behaviour, extreme irritation or exasperation.
to exit from a train or bus. (Only used in a formal context: normally "get off". US: disembark or deboard).
(originally from trademark Ansafone) automated telephone answering device (US and UK also: answering machine).
direction opposite to clockwise (US: counterclockwise).
school for juvenile delinquents; reform school. Note that such institutions have not been referred to officially as "approved schools" since 1969. Juvenile delinquents, depending on their age and level of malfeasance, may now be sent to Secure Units or YOIs (Young Offender Institutions – a correctional facility for juvenile delinquents). (US: juvenile detention center, juvenile hall, (slang) juvie.)
(informal) pushing-and-shoving or outright fighting.
(vulgar; UK and Canada) buttocks (US equivalent: ass), backside or anus, depending on context; to be arsed: to be bothered to do something, most commonly as a negative or conditional (e.g. I can't be arsed, if/when I can be arsed). Sometimes used in the US but only as a noun.
[to fall] arse over tit
(vulgar, alternatively arse over tit/tip) [to fall] head over heels. (US: ass over tea kettle).
(abbreviation of 'articulated lorry') (US: semi, semi-trailer truck, tractor-trailer)
(Scottish) a deep plate or dish.
a solanaceous plant bearing a fruit of the same name, commonly used as a vegetable in cooking (US: eggplant).
a prompting system for television announcers (genericised trademark, after a leading manufacturer) (US: teleprompter).
London West Indian term for an arse or a homosexual, e.g. "Batty Boy". The word "botty", used by children to refer to the backside, is pronounced "batty" in the West Indian accent. More generalled used to mean "mad" as in crazy.
(vulgar) error, mistake, (see Cock-up) SNAFU
bang to rights
(slang) in the act of committing an offence, red-handed (US: dead to rights)
(1) a sausage (from the tendency of sausages to burst during frying), (2) a firework, (3) an old car (allusion to their tendency to back-fire)
northern usage, a soft white bread roll made with barm as a leavening agent.
soft bread roll or a sandwich made from it; in plural, breasts (vulgar slang)
barmaid *, barman
a woman or man who serves drinks in a bar. Barman and the originally American bartender appeared within a year of each other (1837 and 1836); barmaid is almost two centuries older (circa 1658).
a fight or argument (dialect).
(UK, Canada) a type of lawyer (one qualified to give specialist legal advice and, traditionally, argue a case in both higher and lower law courts). Sometimes used in US with pejorative connotations.
small watercourse; stream; creek (regional, especially Yorkshire and the Lake District)
bedsit (or bedsitter)
one-room apartment that serves as a bedroom and a living room (US: see SRO; compare studio apartment, efficiency)
orange ball containing a flashing light mounted on a post at each end of a zebra crossing (qv); named after the UK Minister of Transport who introduced them in 1934.
a mildly derogatory term for a silly person. The word is an abbreviation of either 'Berkshire Hunt' or 'Berkeley Hunt' (it is uncertain which is the original phrase), rhyming slang for cunt. (Note that 'berk' rhymes with 'work', whereas the first syllable of both 'Berkshire' and 'Berkeley' is pronounced 'bark'.)
to wander aimlessly or stroll/walk without urgency to a destination.
a derogatory term for a woman. Usage varies with a range of harshness from 'bitch', referring to a disagreeable and domineering woman, to only a slightly derogatory term for a young woman (from the Arabic for a girl).
a ballpoint pen. Named after its Hungarian inventor Laszlo Biro (IPA: /ˈbaɪroʊ/)
bish bash bosh
emphatic way of stating that something is simple, and will be/has been easy to do.
(US. Blood Sausage)
(slang) to obtain or achieve by deception, to bluff, to scrounge, to rob, robbery, tall story, bluff, deception
(informal) an exclamation of surprise. (Originally gor blimey, a euphemism for God blind me, but has generally lost this connotation.)
(informal) man, fellow
(informal, mildly vulgar) oh my God!, what the hell!.
blues and twos
(slang, uncommon) emergency vehicle with lights and sirens (emergency services in the UK generally use blue flashing lights and formerly used a two-tone siren) (US: lights and sirens)
long shorts used for surfing or beachwear (US and UK also: board shorts or swimming trunks)
police officer, named after Sir Robert Peel, the instigator of the world's first organised police force
Bob's your uncle
"there you go", "it's that simple". Also used to signify that no further explanation for the situation being described will be forthcoming. Sometimes extended to "Robert's your mother's brother" or "Bob's your uncle, Fanny's your aunt" for emphasis. It derives from the name of a British Prime Minister Arthur Balfour, whose uncle Lord Salisbury (given name Robert), had been his political mentor and also prime minister.
something of low quality or (more commonly) someone who lacks ability at something, (e.g."Our new striker is bobbins")
a poor job (repair) that just about works. See Bodger.
scientist or engineer, sometimes abbreviated to boff
(roll of) toilet paper (slang)
completely ordinary, run-of-the-mill, unadulterated, unmodified
type of confection (US: hard candy)
(vulgar; originally ballocks, colloquially also spelled as bollox) testicles; verbal rubbish (as in "you're talking bollocks") (US: bullshit). The somewhat similar bollix is found in American English, but without the anatomical connotations or vulgar sense meaning 'mess up'. The twin pulley blocks at the top of a ship's mast are also known as bollocks, and in the 18th century priests' sermons were colloquially referred to as bollocks; it was by claiming this last usage that the Sex Pistols prevented their album Never Mind the Bollocks from being banned under British obscenity laws. Related phrases include bollocksed, which means either tired ("I'm bollocksed!") or broken beyond repair; bollocks up, meaning to mess up ("He really bollocksed that up"); and [a] bollocking, meaning a stern telling off.
The dog's bollocks is a fairly common phrase used in British English, although this has the opposite meaning – something described as "The dog's bollocks" or sometimes even just "The bollocks" is something considered to be very good. In mixed company this phrase may be toned down to "The mutt's nuts", or the phrase "The bee's knees" (the business) may be used as a polite substitute. The etmyology of this expression is said by some to derive from printers' slang for the punctuation symbol ':-' when printing involved the use of carved metal blocks to form typesetting.[clarification needed]
the back compartment of a car. (American: trunk)
bonce : (informal) person's head (mainly used in London and the South East, though said in the North too)
cold – from "cold enough to freeze the balls off a brass monkey". This phrase is often said to derive from cannonballs stowed on a brass triangle named after a "powder monkey" (a boy who runs gunpowder to the ship's guns) spilling due to the frame's contraction in cold weather. However this is doubtful since these were wooden (possibly for this reason) and its more obviously vulgar derivation may be the correct one.
(musical) a note of two bar's (or a count of 8) length in 4/4 time
(vulgar, rhyming slang) breasts; from football team Bristol City = titty
bubble and squeak
dish of cooked cabbage fried with cooked potatoes and other vegetables. Often made from the remains of the Sunday roast trimmings. (Irish: colcannon)
little or nothing at all; "I asked for a pay rise and they gave me bugger all"; "I know bugger all about plants"; damn it all. US: zip, jack or (offensive) jack ****.
an institution that provides mortgage loans and other financial services (US equivalent: savings and loan association)
a bag worn on a strap around the waist (US: fanny [DM] pack)
useless paperwork or documentation; from "bum fodder" toilet paper)
bureau de change
an office where money can be exchanged (US: currency exchange)
(originally colloquial, back-formation from burglar) to commit burglary (in the US, burglarize is overwhelmingly preferred, although burgle is occasionally found).
1: * to play live music, perform or otherwise entertain in a public place, usually in the hope of receiving small monetary contributions from spectators and passersby. American English has no exact equivalent, but a busker is a "street musician" or "street performer". Gradually, "busk" (v) and "busker/busking" (n) are becoming increasingly common in US English usage, at least among professional musicians.
2: used to imply rapid improvisation in a working environment, for example: "we'll have to busk it" (we'll have to make it up as we go along). The latter meaning comes from the former, specifically from the concept of performing without sheet music or script.
(North England colloquialism, also understood in the south) a buttered sandwich, sometimes with chips [DM] (chip butty)
(Northern and Central England) a workmate, and thus an unpowered barge towed by a powered one, such as a narrowboat
(Welsh English colloquialism) friend, similar to usage of word mate (usually "bwty").