1 British spelling. Follow standard British usage, but remember that influences are crossing the Atlantic all the time (for example, the spellings program and disk have become normal British usage in information technology, while sulfur has replaced sulphur in scientific and technical usage). Note, however, that the names of US bodies may retain the original spellings, e.g. Department of Defense.
Do use a spellchecker, set to UK English, as an aid. Remember, though, to use your judgment and in case of doubt check in a dictionary or indeed this Guide.
2 Words in -ise/-ize. Use -ise. Both spellings are correct in British English, but the -ise form is now much more common in the media. Using the -ise spelling does away with the need to list the most common cases where it must be used anyway. (There are up to 40 exceptions to the -ize convention: the lists vary in length, few claiming to be exhaustive.)
The spelling organisation should thus be used for all international organisations, even if they more commonly use the -ize spelling, e.g. International Labour Organisation (its website uses International Labour Organization, while Americans will write International Labor Organization). However, following the rule in 2.1 above, the spellings of bodies native to the USA and other countries that use the –ize spelling may be retained.
3 The -yse form for such words as paralyse and analyse is the only correct spelling in British English.
4 Digraphs. Keep the digraph in aetiology, caesium, oenology, oestrogen, etc. (etiology etc. are US usage), but note that a number of such words (e.g. medieval and fetus) are now normally spelt without the digraph in British English. Foetus is still common in Britain in non-technical use.
5 Double consonants. In British usage (unlike US practice), a final -l is doubled after a short vowel on adding -ing or -ed to verbs (sole exception: parallel, paralleled) and adding -er to make nouns from verbs:
travel, travelling, travelled, traveller
level, levelling, levelled, leveller
Other consonants double only if the last syllable of the root verb is stressed or carries a strong secondary stress:
admit, admitting, admitted
refer, referring, referred
format, formatting, formatted
benefit, benefiting, benefited
focus, focusing, focused
combat, combating, combated
target, targeting, targeted
Exception: a few verbs in -p (e.g. handicapped, kidnapped, worshipped, unlike developed).
6 Carcass/carcase. Prefer carcass(es) to carcase(s), except when citing official texts that use the latter.
7 Input/output. Avoid the forms inputted and outputted; write input and output: e.g. 70 000 records were input last month.
8 Use –ct– not –x– in connection, reflection, etc. But note complexion and flexion.
9 Write gram, kilogram (not gramme, kilogramme). However, use tonne not ton (‘ton’ refers to the non-metric measure).
10 Write metre for the unit of length, meter for measuring instruments.
11 A(n) historical. The use of an rather than a before words such as historical or hotel dates back to a time when the ‘h’ was never pronounced in these words. While you should now write a hotel, an historical event is still regarded as acceptable, presumably because the ‘h’ is still frequently dropped in even careful speech, so you may choose which form you prefer.
12 Judgment. The European Courts use the form without the -e- in the middle, and this practice should be followed for EU purposes.
13 Tricky plurals. Follow the list below.
|appendix||appendices (books), appendixes (anatomy)|
|focus||foci (mathematics, science) focuses (other contexts)|
|formula||formulas (politics) formulae (science)|
|forum||forums or fora|
|index||indexes (books), indices (science, economics)|
|maximum||maxima (mathematics, science) maximums (other contexts)|
|medium||mediums (life sciences, art), media (press, communications, IT)|
|memorandum||memorandums or memoranda|
|papyrus||papyri or papyruses|
|referendum||referendums or referenda|
|spectrum||spectra (science), spectrums (politics)|
|symposium||symposiums or symposia|
Source: European Commission Directorate-General for Translation
A handbook for authors and translators in the European Commission
Seventh edition: August 2011 Last updated: May 2014