Biro is a trade name and misuse is aggressively policed, so cap; generic alternative is ballpoint pen
birthday people and animals have birthdays; everything else has anniversaries. Write 33rd birthday, 65th birthday etc (any number higher than tenth)
birthrate, birthright, birthplace no hyphens; but birth control, birth certificate etc
bisexual pronouns he and his can no longer refer to both sexes equally; he or she will sometimes do. Always be sensitive in this contentious area. It is often easier to use the plural they, for he or she, and sometimes even the ugly their for his or her. Do this only when necessary. Do not, for instance, write “one of the Chelsea players threw their shirt into the crowd”, or “each nun has their own list of tasks” — the sex of those involved in both cases is quite clear and should be stated
bishops once consecrated they are bishops for life unless defrocked; retirement from a see does not make anyone “a former bishop”
bit abbreviate to b; thus kilobit (kb), megabit (Mb) etc
bite (as with teeth) must not be confused with the computing term byte or the geographical bight
blacklist one word as noun or verb
blackout noun, one word
black (people), lower case; do not use “non-white” or “coloured” — and never “immigrants” (which many are not). Unless you want to evoke South Africa under apartheid, prefer “black people” to “blacks”. Be sensitive to local usage: African-American is now standard usage in the United States, for instance, while Afro-Caribbean (or African-Caribbean) and Black British are widely used in the UK. See also coloureds, race
blackspot (accident, unemployment etc), one word; similarly, troublespot, hotspot
blame take care with this word; blame is attached to causes, not effects. So say “Bad weather is blamed for my bronchitis”, NOT “My bronchitis is blamed on bad weather”
bloc use in context such as the former Soviet bloc, a power bloc etc; but block vote
blond (noun and adjective) for men, blonde for women; but all should have blond hair
blood groups write, eg O negative (no hyphen)
bloodied but unbowed, a cliché best avoided, but written thus if used; but red-blooded etc
blood sports two words; similarly field sports, motor sports
bloody mary lower case for the cocktail of tomato juice and vodka
blowsy prefer to blowzy
blue lower case for an Oxbridge sportsman or woman and for the award itself
blue-chip hyphen as modifier, eg a blue-chip company
blue-collar workers as white-collar workers
blueprint avoid this greatly overworked word when all you mean is plan, scheme or proposal
bluetongue one word for the notifiable disease afflicting ruminants
bluffers be very cautious. The Bluffer’s Guide/Guides are trademarks, rigorously protected by their publishers. So generic phrases such as “a bluffer’s guide to …” must be avoided
Blu-Tack proprietary so must cap
boat is generally used of a small vessel, including fishing boats up to the size of a trawler; a ship is a large seagoing vessel big enough to carry smaller boats. In the Royal Navy, submarines are called boats. All take the pronoun she and the possessive her
Boat Race caps for the annual Oxford-Cambridge race on the Thames
Bobcat should not be used in a generic sense as a description of skid-steer loaders or other equipment
Boche derogatory slang for Germans; Bosch, the household appliance or power tools manufacturer
bodyline one word, no quotes for the cricketing tactic; use lower case in general usage such as bodyline bowling but cap for the Bodyline tour (of the 1932–33 Ashes)
boffin avoid as a synonym of scientist, except ironically or in direct quotes
Bogart, Humphrey but (Sir) Dirk Bogarde
bogey (golf, plural bogeys); bogie (wheels); bogy (ghost); but note bogeyman
Bohemia, Bohemian cap only in specific reference to the geographical entity but lower case bohemia, bohemian metaphorically
Bolshevik
bolshie lower case for rebellious; cap in (derogatory) political context
bolt hole two words
bombs car bomb, fire bomb, nail bomb, petrol bomb, suicide bomb etc; but hyphenate verbal or adjectival use, eg to fire-bomb, a nail-bomb attack
bombshell in metaphorical use, as in “drop a bombshell”, is a cliché. Avoid
bonanza another greatly overworked word that should be avoided wherever possible
Bonfire Night initial caps; see Guy Fawkes Night
Book of Common Prayer, the roman
bookshop
boom overused word
Boötes pronunciation requires a diaeresis on the name of the constellation, should you ever have to refer to it
border lower case, even the one between England and Scotland (north of the border); cap the (Scottish) Borders; remember that the border is not marked by Hadrian’s Wall
bored with/by not of
-born normally prefer to use nationality, rather than country, eg English-born, but there are exceptions, eg Singapore-born; for counties, cities etc, normally use the noun, eg London-born, Manchester-born, Dorset-born, but again there are exceptions, eg Cornish-born
born/borne the second is what you want except when writing about birth. Something to be borne in mind; a theory borne out by the facts; an initiative (or a tree) that has borne fruit; shame borne in silence etc
borstals no longer exist; they are now young offender institutions
bortsch Russian or Polish soup
Bosphorus a strait, not a river
Botox trade name, so must cap
bow tie no hyphen
box office as noun, two words; but hyphenate when adjectival (eg box-office success)
box sets boxed sets may be more logical for the collections of CDs, DVDs etc, but no one says it; we must concede defeat
boy band two words. Note also girl band