Acronym

== Nomenclature ==
Whereas an [[abbreviation]] may be any type of shortened form, such as words with the middle omitted (for example, ''Rd''. for ''Road'' or ''Dr''. for ''[[Doctor (title)|Doctor]]'') or the end cut off (as in ''Prof.'' for ''Professor''), an acronym or initialism is—in the broad sense—formed from the first letter or first few letters of each important word in a phrase (such as ''[[AIDS]]'', from ''acquired immunodeficiency syndrome'', and ''[[scuba diving|scuba]]'' from ''self-contained underwater breathing apparatus'').<ref name="Brinton_Page_109">{{cite book |last1=Brinton |first1=Laurel J. |last2=Brinton |first2=Donna M. |title=The Linguistic Structure of Modern English |date=2010 |publisher=John Benjamins Publishing Company |location=Amsterdam |isbn=978-90-272-8824-0 |page=109 |url= https://books.google.com/books?id=1EeND5SyUuwC&pg=PA109 |access-date=April 3, 2022}}</ref> However, this is only a loose rule of thumb, as some acronyms are built in part from the first letters of [[morpheme]]s (word components; as in the ''i'' and ''d'' in ''immuno-deficiency'') or using a letter from the middle or end of a word, or from only a few key words in a long phrase or name. Less significant words such as ''in'', ''of'', and ''the'' are usually dropped (''NYT'' for ''[[The New York Times]]'', ''DMV'' for ''[[Department of Motor Vehicles]]''), but not always (''TICA'' for ''[[The International Cat Association]]'', ''DOJ'' for ''[[United States Department of Justice|Department of Justice]]'').

{{Anchor|initialism}}Abbreviations formed from a string of initials and usually pronounced as individual letters (as in ''FBI'' from ''[[Federal Bureau of Investigation]]'', and ''e.g.'' from Latin {{lang|la|[[List of Latin phrases (E)#exempli gratia|exempli gratia]]}}) are sometimes more specifically called [[wiktionary:initialism|initialism]]s<ref name="Brinton_Page_110" /> or [[wiktionary:alphabetism|alphabetism]]s. Occasionally, some letter other than the first is chosen, most often when the pronunciation of the name of the letter coincides with the pronunciation of the beginning of the word (example: ''BX'' from ''[[base exchange]]''). Acronyms that are usually pronounced as words, such as ''AIDS'' and ''scuba'', are sometimes called '''''word acronyms'''''; this is done to differentiate them more clearly from initialisms, especially since some users of the term "initialism" use "acronym" in a narrow sense meaning only the type sounded out as letters. Another sub-type of acronym (or a related form) is the '''''[[Abbreviation#Syllabic abbreviation|syllabic abbreviation]]''''', which is composed specifically of multi-letter [[Syllable|syllabic]] (even multi-syllabic) fragments of the shortened words such as ''[[Interpol]]'' from ''international'' + ''police'', though its full proper name in English is the ''International Criminal Police Organization''. Usually the first syllable (or two) is used from each major component word, but there are exceptions, such as the U.S. Navy term ''DESRON'' or ''DesRon'' from ''destroyer squadron''.

There is no special term for abbreviations whose pronunciation involves the combination of letter names with words, or with word-like pronunciations of strings of letters, such as ''[[JPEG]]'' ({{IPAc-en|ˈ|dʒ|eɪ|p|ɛ|ɡ}} {{respell|JAY|peg}}) and ''[[MS-DOS]]'' ({{IPAc-en|ˌ|ɛ|m|ɛ|s|ˈ|d|ɒ|s}} {{respell|em|ess|DOSS}}). Similarly, there is no unique name for those that are a mixture of syllabic abbreviations and initialisms; these are usually pronounced as words (e.g., ''[[radar]]'' from ''radio detection and ranging'', consisting of one syllabic abbreviation and three single letters, and ''[[sonar]]'' from ''sound navigation ranging'', consisting of two syllabic abbreviations followed by a single acronymic letter for ''ranging''); these would generally qualify as word acronyms among those who use that term. There is also some disagreement as to what to call an abbreviation that some speakers pronounce as letters but others pronounce as a word. For example, the terms ''[[Uniform Resource Locator|URL]]'' and ''IRA'' (for ''[[individual retirement account]]'') can be pronounced as individual letters: {{IPAc-en|ˌ|juː|ˌ|ɑːr|ˈ|ɛ|l}} {{respell|ew|ar|EL}} and {{IPAc-en|ˌ|aɪ|ˌ|ɑːr|ˈ|eɪ}} {{respell|eye|ar|AY}}, respectively; or as a single word: {{IPAc-en|ɜːr|l}} {{respell|URL}} and {{IPAc-en|ˈ|aɪ|r|ə}} {{respell|EYE|rə}}, respectively. The same character string may be pronounced differently when the meaning is different; ''IRA'' is always sounded out as ''I-R-A'' when standing for ''[[Irish Republican Army]]''.

{{Anchor|Expansion}}The spelled-out form of an acronym, initialism, or syllabic abbreviation (that is, what that abbreviation stands for) is called its ''expansion''.