This is an abbreviated list of words to watch. UK versus US spelling can be tricky.

(Exhaustive list of UK versus US spellings can be found in this list.)

Don't forget to check out the style guide.

Accepted WordUnacceptable WordDetail
accessory   Spell with a double c and a double s; the ending is -ory.
accommodate   Spell with a double c and a double m and an o before and after the m's.
Administrator administrator Always capitalise when referring to the Joomla! User level or the Back-end Administrator. (Use of the latter should be limited to avoid confusion. Refer to this area as the Control Panel when referring to the facilities and Back-end when comparing to the Front-end.
address   Spell with a double d.
ageing aging  
a lot alot Use as two words, not one.
amend and amendment   Spell with a single m at the beginning.
analogue analog  
apologise apologize Spell with -olo- in the middle.
apparent   Use double p but only one r and end in -ent.
argument   Do not put an e after the u, as you would in argue.
Article   Capitalise the word Article when referring to the element of Joomla! content.
AutoCorrect   One word with capitalisation as shown
Back-end backend Ensure it is always capitalised and hyphenated when referring to the Administrator area of Joomla! Do not capatalise when referring to your own.
backup and back up   Use backup when used as an adjective, as in "he had a backup disk in his bag" and use back up when using it as a verb, as in "don’t forget to back up your hard drive".
Banner   Capitalise the word Banner when referring to the element of the Joomla! Banner Component.
bitmap bit map or bit-map One word not hyphenated or two words.
business bisiness Spell with busi- at the beginning
capitalisation capitalization UK spelling
catalogue catalog  
Category (Manager)   Capitalise the word Category when referring to the element of Joomla! content.
centre center  
command comand  
Contact (Manager)   Always capitalise when referring to the Component element or Manager function.
checkbox check box  
check-in (noun/adjective) (Global) Check-in checkin (noun/adjective) We will be using check-in, which must be capitalised when referring to a specific function, Menu Item, or button such as Global Check-in. It is correct to use check in (verb) as in "check in your materials".
Component (Manager)   Capitalise the word Component when referring to an Extension in Joomla!.
Contact   Capitalise the word Contact when referring to the element of the Joomla! Contact Component.
Control Panel control panel Capitalise when referring to the Joomla! Back-end functional area.
CSS css Always capitalise except in code or when a file extension.
database data base One word not two
dial-up dialup dial up Include the hyphen between "dial" and "up".
disappoint and disappointment dissapoint disapoint dissappoint Remember to spell with one s and a double p.
e-mail E-mail email E-mail is obviously correct at the start of a sentence! We will be going with e-mail (lower-case and hyphenated) for consistency.
Extension(s) extension(s) Refer to Components, Modules, and Plugins collectively as Extensions. Always capitalise when referring to CMPT’s
encyclopedia encylopedia  
extraordinary extrordinary Do not omit the “a” of extra.
FAQ faq, faqs Abbreviation for frequently asked questions.
fascinate and fascination facination Spell with an s before the c.
favourite favorite  
file name filename Two words rather than one.
friend   Spell with -ie- in the middle.
Front-end frontend Ensure it is always capitalised and hyphenated when referring to the User (public) area of Joomla!
Front Page front page Frontpage frontpage Always two words. Capitalise the words Front Page when referring to the Menu Item element of Joomla! content.
fulfil fulfill Spell with one l in the middle and one at the end
gateway gate way One word, not two.
gauge gage Spell with -au- in the middle.
grateful gratful or graitful Begin with grate-. Single ‘l’ at the end
hard disk hard-disk Two words. No hyphenation
hardware hard-ware One word. No hyphenation
home page homepage Always two words.
HTML HTM html Always capitalise, except in code or when a file extension.
hypocrisy hypocrasy hypocrisey Begin with hypo- and end with -isy.
immediate and immediacy imediate Spell with a double m.
independent independant End with –ent rather than -ant.
instalment installment Spell with one l
JavaScript javascript Java Script One word but with the J and S capitalised.
Joomla! joomla Capitalise everytime and include the exclamation mark.
the JCM J!CM, jcm Abbreviate the second reference to the Joomla! Community Magazine as JCM. Always use the <acronym> tag for accessibility. Don't forget to use "the" before JCM
joomla_root/   Use as the starting point to all references to directories within the core installation to avoid confusion with the web server or database root.
keyboard key board One word not two
licence and license license Use licence as a noun for the permit you obtain to do something like hunt or drive, but use license when you mean it as a verb, to give permission to or allow someone to do something or for something to occur.
login, logon, logoff, and logout   Noun always one word one “g” the act of logging into or out of a computer or Web site.
log in, log on, and log off log out   Verb to go through the procedure of logging in to or out of a Web site for example
maintenance maintainence Spell with -ten- in the middle and end with -ance.
Mambot mambot Always capitalise when used for a Joomla! Extension. Remember from 1.5 this is replaced by Plugin.
Manager manager When referring to either the User level or a Manager screen (Poll Manager) it is capitalised.
Media Manager media manager Capitalise when referring to the Joomla! function.
Menu menu When referring to a specific menu in Joomla! always capitalise.
Menu Item menu item Two words and capitalise both when referring to the specific element within Joomla! but not when generally discussing any old menu items
metadata meta data One word
millennium   Spell with a double l and a double n.
misspell mispell Spell with a double s.
Module module Always capitalise when used for a Joomla! Extension.
multitasking multi-tasking multi tasking one word
MySQL mysql MYSQL  
News Feed (Manager) newsfeed Newsfeed Always capitalise when referring to the Component within Joomla!, and always two words. Manager when included is always capitalised
necessary and necessity neccessary Spelled with one c and a double s.
occasion occassion Spell with a double c and a single s.
OK Ok, ok capitalise both letters. Do not use okay.
omission ommission Spell with one m and a double s.
online on-line on line One word
Open Source (OS) open source Capitalise the O and S.
original   Spell with an i before and after the g.
overwrite over write over-write One word
password pass word One word
PHP php Always capitalise except when used as a file extension or in code
Poll (Manager) poll manager Always capitalise when referring to the Component in Joomla!.
platform    
Plugin(s)   One word, always capitalise when referring to the Extension.
possess and possession posess Spell with a double s before and after the e.
PostScript Post Script post-script One word. Capitalise P and S.
practice and practise   Use practice as a noun when describing actually doing something rather than just discussing it or theories about it, as in “put your good manners into practice”. Use practise as the verb, “improving your skill by doing something over and over”.
presence presance End with -ence.
privilege privilage privildge Spell with -ege at the end.
proofread proof-read, proofed, proof read This applies to all derivatives as well, such as proofreader, proofreading, etc.
questionnaire questionare Spell with a double n and end with -aire.
really realy Spell with a double l in the middle.
receive recieve Use i before e except after c.
recommend and recommendation reccomend Spell with a single c and a double m.
rhythm writhm  
secretary secratary secretery Use an e after the r and end with -ary.
Section section Always capitalise when referring to the specific element within Joomla! cms.
seize sieze Spell with the e before the i.
separate seperate Spell with -par- in the middle.
similar simalar simillar similer End with –lar rather than -ler.
skilful, skilfully, skilfulness skillfull Watch for variations as shown
smart phone smartphone Two words based on entries in various writing style guides.
software soft ware soft-ware One word
source code sourcecode Two words
style sheet stylesheet style-sheet Two words no hyphen
subdirectory sub-directory sub directory One word
subdocument sub-document sub document One word
success and successful sucess Spell with a double c and a double s.
sufficient suficient Use a double f in the middle and end with -cient.
Super Administrator super administrator Always capitalise when referring to the Joomla! User level.
surprise   Spell with an r before and after the p.
toolbar tool bar tool-bar One word
travelling traveling In British English, words that end in -l preceded by a vowel usually double the -l when a suffix is added, while in American English the letter is not doubled. The letter will double in the stress is on the second syllable.
unfortunately   Spell with -ately at the end.
URL Url url Capitalise except when used in code.
User user When referring to a specific Joomla! User always capitalise first letter
vehicle   Spell with -icle at the end.
Web web Capitalise except when using to refer to a spiders trap!
Web link
Web Link
weblink
web-link
Two words unhyphenated.
Capitalise the words when discussing the Component variant - Web Link Manager.
website Website
Web Site
web site
A location on the World Wide Web that maintains one or more pages at a specific address. Also, webcam, webcast and webmaster. But as a short form and in terms with separate words, the Web, Web page, Web link and Web feed.
weird wierd Spell with the e before the i
who whom   Who is the pronoun used for references to human beings and to animals with a name. It is grammatically the subject (never the object) of a sentence, clause or phrase: The woman who rented the room left the window open. Who is there?
Whom is used when someone is the object of a verb or preposition: The woman to whom the room was rented left the window open. Whom do you wish to see?
withhold withold Spell with a double h in the middle.
World Wide Web (WWW) Worldwide Web Capitalise, as it is a proper noun. Three separate words. Capitalise the abbreviation (except in URL’s)