This guideline covers the use of abbreviations, including initialisms, acronyms, contractions and shortenings, in the English Wikipedia. An initialism is usually formed from some or all of the initial letters of words in a phrase. In some variations of English, an acronym is considered to be an initialism which is pronounced as a word (e.g. NATO), as distinct from the case where the initialism is said as a string of individual letters (e.g. "UN" for the United Nations). Herein, the term acronym applies collectively to initialisms, without distinction that an acronym is said as a word.

Maintaining a consistent abbreviation style will allow Wikipedia to be read, written, edited, navigated and used more easily by readers and editors alike. The style should always be consistent within a page. If a guideline conflicts with the correct usage of a proper name, ignore it. The abbreviation style used in quotations from written sources should always be written exactly as in the original source, unless it is a Wikipedia-made translation.

Always consider whether it is better to simply write a word or phrase out in full, thus avoiding potential confusion for those not familiar with its abbreviation. Remember that Wikipedia does not have the same space constraints as paper.

Use sourceable abbreviations[edit]

Avoid making up new abbreviations, especially acronyms. For example, "International Feline Federation" is good as a translation of Fédération Internationale Féline, but neither the anglicization nor the reduction IFF is used by the organization; use the original name and its official abbreviation, FIFe.

If it is necessary to abbreviate in "small spaces" (infoboxes, navboxes and tables), use widely recognized abbreviations. As an example, for New Zealand gross national product, use NZ and GNP, with a link if the term has not already been written out: NZ GNP; do not use the made-up initialism NZGNP).

Full stops (periods)[edit]

Modern style is to use a full stop (period) after a shortening (although there are many exceptions) but no full stops with an acronym. In the case of an acronym containing full stops between letters, it should also have a full stop after the final letter. If an abbreviation ending in a full stop ends a sentence, do not use an extra full stop (e.g. New York is in the U.S. and not New York is in the U.S..).

Contractions that contain an apostrophe (don't, shouldn't, she'd) never take a period (except at the end of a sentence, of course). They are also not used except in quotations or titles of works, as noted below. Contractions that do not contain an apostrophe almost always take a period in North American English, but the stop is optional in British English: Doctor can be abbreviated Dr. in American and Canadian English, but Dr. or Dr in British English. If in doubt, or if the dot-less usage could be confusing in the context, use the stop. An exception is units of measurement, which never use periods. (see WP:Manual of Style/Dates and numbers).

Acronyms[edit]

Acronyms are abbreviations formed, usually, from the initial letters of words in a phrase.

• Capitalisation: Some acronyms are written with all capital letters, some with a mixture of capitals and lower-case letters and some are written as common nouns (e.g. laser). Acronyms whose letters are pronounced individually (which is what some call "initialisms", for example FBI, EU) are written in capitals. For more guidance on the capitalisation of acronyms, see Wikipedia:Manual of Style/Capital letters#Acronyms.
• Spacing: The letters of acronyms should not be spaced.
• Plurals: Plural acronyms are written with a lower-case s after the abbreviation, without an apostrophe, unless full stops are used between the letters (e.g. ABCs or A.B.C.'s). Note that Wikipedia generally avoids using full stops in upper-case acronyms.

If there is an article about the subject of an acronym (i.e. NATO), then other articles referring to or using the acronym should use the same style (capitalisation and punctuation) that has been used within the main article. If no article exists for the subject acronym, then style should be resolved by considering consistent usage in source material.

Unless specified in the "Exceptions" section below, an acronym should be written out in full the first time it is used on a page, followed by the abbreviation in parentheses, e.g. Millennium Development Goals (MDGs). Common exceptions to this rule are post-nominal initials because writing them out in full would cause clutter. Another exception is when something is most commonly known by its acronym (i.e., its article here is at the acronym title), in which case the expansion can come in the parenthetical or be omitted, except in the lead of its own article: according to the CIA (U.S. Central Intelligence Agency).

To save space in small spaces (defined above), acronyms do not need to be written out in full. When not written out in full on the first use on a page, an acronym should be linked. An unambiguous acronym can be linked as-is, but an ambiguous acronym should be linked to its expansion. Upon later re-use in a long article, the template {{abbr}} can be used to provide a mouse-over tooltip giving the meaning of the acronym again without having to redundantly link it or spell it out again in the main text: {{abbr|CIA|U.S. Central Intelligence Agency}}, giving: CIA

For partial acronyms formed using the now-rare convention of including whole short words in them, do not blindly "normalize" them to typical current style, but write each as found in the majority of modern reliable sources. Examples: "Commander-in-Chief" is generally abbreviated CinC on its own, but may appear in all-caps when used in a longer acronym (especially a U.S. government one) like CINCFLEET and CINCAIR. The Billiard Association of America was known as BA of A; while this should not be written as unsourceable variations like BAofA or BAA, the awkwardness of the abbreviation to modern eyes can be reduced by replacing the full-width spaces with thin-space characters: BA{{thinsp}}of{{thinsp}}A or BA of A gives BA of A, which better groups the letters into a unit.

Exceptions[edit]

Countries and multinational unions[edit]

For these commonly referred to entities, the full name does not need to be written out in full on first use, nor provided on first use in parentheses after the full name if written out.

• Ship names*

Ship name prefixes like HMS and USS should not be written out in full.

Time Zones* Abbreviations for time zones (e.g. GMT and UTC) should not be written out in full in times.

Acronyms in this table do not need to be written out in full upon first use, except in their own articles or where not doing so would cause ambiguity.

Miscellanea[edit]

Acronyms in page titles[edit]

Acronyms should be used in a page name if the subject is known primarily by its abbreviation and that abbreviation is primarily associated with the subject (e.g. NASA; in contrast, consensus has rejected moving Central Intelligence Agency to its acronym, in view of arguments that the full name is used in professional and academic publications). In general, if readers somewhat familiar with the subject are likely to only recognise the name by its acronym, then the acronym should be used as a title.

One general exception to this rule deals with our strong preference for natural disambiguation. Many acronyms are used for several things; naming a page with the full name helps to avoid clashes. For instance, multiple TV/radio broadcasting companies share the initials ABC; even though some may be far better known by that acronym, our articles on those companies are found at, for example, American Broadcasting Company rather than ABC (U.S. TV network). A useful test to determine what an abbreviation usually refers to can be done by checking Acronym Finder or Abbreviations.com and finding the relative usage. If it is found that a particular subject is overwhelmingly denoted by an unambiguous acronym, the article title on that subject can be expressed as the acronym and a disambiguation page can be used for the other subjects.

In many cases, no decision is necessary because a given acronym has several expansions, none of which is the most prominent. Under such circumstances, an article should be named with the spelled-out phrase and the acronym should be a disambiguation page providing descriptive links to all of them. See, for example, "AJAR", which disambiguates between "African Journal of AIDS Research" and "Australian Journal of Agricultural Research". A title like AJAR (African journal) should be avoided if at all possible. If the acronym and the full name are both in common use, both pages should exist, with one redirecting to the other (or as a disambiguation page).

Acronyms as disambiguators[edit]

To save space, acronyms should be used as disambiguators, when necessary. For example, "Great Northern Railway (U.S.)" and "Labour Party (UK)". The abbreviations are preferred over United States and United Kingdom, for brevity.

To help navigation, please create redirects that contain (US) and (U.S.). For example, "Great Northern Railway (US)" should redirect to "Great Northern Railway (U.S.)" (or the other way around).

Acronyms in category names[edit]

Contractions[edit]

A contraction is an abbreviation of one or more words that has some or all of the middle letters removed but retains the first and final letters (e.g. Mr and aren't). Missing letters are replaced by an apostrophe in multiple-word contractions. Contractions should not be used in Wikipedia.

Prefix titles such as Mr and Dr should not be used. Prefixes of royalty and nobility should be used, however (in accordance with a relevant style guide), but should not be abbreviated. (See Wikipedia:Naming conventions (people)#Titles and styles and Wikipedia:Naming conventions (royalty and nobility).)

Initials[edit]

Only use initials in a personal name if the name is commonly written that way. See Wikipedia:Manual of Style/Biographies for when to use full names and other formats.

An initial is followed by a full stop (period) and a space (e.g. J. R. R. Tolkien), unless:

• A strong majority of reliable sources do otherwise for that person (see Wikipedia:Naming conventions (people)); examples include CC Sabathia, k.d. lang, and Jeb Bush.
• The person had or has a different preferred style for his or her own name. In that case: treat as a self-published name change.

In article text, a space after [a full stop following] an initial should be a non-breaking space: J. R. R. Tolkien (or use the {{nbsp}} template).

Shortenings[edit]

A shortening is an abbreviation of a word for which at least the last letter has been removed (e.g. etc. and rhino). Some shortenings also contain letters that are not present in their expansion (e.g. bike). Whether or not to follow a shortening with a full stop often comes down to individual cases, but, as a general rule, use a full stop after a shortening that only exists in writing (e.g. etc.) but not for a shortening that is used in speech (e.g. rhino). Common sense should be applied to judge whether a shortening is acceptable in prose or not. Words such as rhino and bike should be avoided; etc. should be used over et cetera, and informal terms, such as wanna, are not used in Wikipedia articles. Uncommon shortenings should be linked on the first use on a page.

Song-writing credits[edit]

Outside of prose, trad. and arr. may be used in song-writing credits to save space. On first usage, use {{trad.}} and {{arr.}}, which will display a mouse-over tooltip expanding the abbreviation.

Miscellaneous shortenings[edit]

Symbols[edit]

Unit symbols[edit]

Miscellaneous symbols[edit]

• Ampersands (&) should only be used in small spaces such as tables and infoboxes, but, preferably, should be avoided even there.
• The at sign (@) should not be used in the place of at in normal text.

Latin abbreviations[edit]

In normal usage, abbreviations of Latin words and phrases should be italicised, except AD, c., e.g., etc. and i.e., which have become ordinary parts of the English language. The expansions of Latin abbreviations should still be italicised, as with most foreign words and phrases (Anno Domini, circa, exempli gratia, et cetera, id est). These are not normally used in article prose.

Do not use &c. in the place of etc.

Abbreviations widely used in Wikipedia[edit]

Wikipedia has found it both practical and efficient to use the following abbreviations, although some can often be replaced by unabbreviated equivalents (that is for i.e., namely for viz., and so on). Versions of non-acronym abbreviations that do not end in stops (periods) are more common in British than North American English, and are always abbreviations that compress a word while retaining its first and last letters, rather than truncating. That said, US military ranks are often given without this punctuation. The Manual of Style on abbreviations, above, eschews the use of periods with acronyms (M.D., Ph.D.).

Special considerations[edit]

• Postal codes and abbreviations of place names (e.g. Calif. (California), TX (Texas), Yorks (Yorkshire) should not be used to stand in for the full names in normal text. The practice is common when specifying places of publication in source citations, especially after the first occurrence.
• "Saint" vs "St" or "St." in placenames should depend upon the official usage.
• Abbreviations should be written in the same fashion each time they are used within the same page (e.g. "US" and "U.S." should not be alternated). Any special cases should have a natural reason (perhaps a list of officers in a joint British–American taskforce) that should be obvious to the reader; stating such a reason in a hidden note will help other editors to maintain it.

See also[edit]

• American and British English differences#Punctuation
• Wikipedia:Edit summary legend
• Wikipedia:Manual of Style#Acronyms and abbreviations
• Wikipedia:Manual of Style/Capital letters#Acronyms
• Wikipedia:Naming conventions (aircraft)
• Wikipedia:Naming conventions (ships)