Initialisms, Acronyms, Contractions: Types of Abbreviations
Abbreviations may be acronyms, initialisms, contractions, or just shortened forms of words.
- Initialism: Letters of the abbreviation individually pronounced
UK, USA, ATM, CEO, FYI, a.m.
- Acronym: Pronounced as a single word
NASA, NATO, UNICEF, LAN, laser, scuba
- Contractions: Some letters omitted to make the word shorter
Mr., Dr., Jr., Sr., Ltd., Sgt.
- Other shortened forms: Only the first syllable or letters retained
Jan., Sun., Inc., Rev., Gen., etc.
Initialisms
The most common form of an abbreviation is an initialism, formed using the first letters of the words of a term. In an initialism, each of the letters is pronounced. Here are some popular ones.
- DIY: do it yourself
- FWIW: for what it’s worth
- TBD: to be decided
- FYI: for your information
- FTR: for the record
Names of countries, organizations, and departments can be abbreviated to form an initialism.
- USA: United States of America
- UK: United Kingdom
- EU: European Union
- UN: United Nations
- NSA: National Security Agency
- DOJ: Department of Justice
- HR: Human Resources
The IT world is littered with initialisms.
- IT: information technology
- URL: uniform resource locator
- PDF: Portable Document Format
- FTP: file transfer protocol
- API: application programming interface
- CPU: central processing unit
- TLA: three-letter acronym
And so is the corporate world.
- CEO: chief executive officer
- VP: vice president
- BA: business analyst
- KRA: key result area
- SLA: service level agreement
Here are some initialisms from Internet slang, popular since the chat-room days of the nineties.
- OMG: oh my god!
- ROFL: rolling on the floor, laughing
- TTYL: talk to you later
- IRL: in real life
Academia though is probably where it all began.
- BCE: before the Common Era
- OE: Old English
- QED: quod erat demonstrandum, or “which was to be demonstrated”
- PS: postscriptum, or “postscript”
- NB: nota bene, or “note well”
An initialism need not always contain only capital letters.
- mph: miles per hour
- ppm: parts per million
- ac: alternating current
- dc: direct current
Don’t capitalize the words in the full form of an abbreviation unless the term is a proper noun. (Excessive capitalization makes text difficult to read.)
- USA: United States of America
a proper noun, the name of a country
- FTP: file transfer protocol
not a proper noun, not capitalized
- FBI: Federal Bureau of Investigation
the name of an agency, and a proper noun
- TBD: to be decided
not a proper noun, therefore not capitalized
Acronyms
An acronym is an abbreviation that is pronounced as a word. For example, UN, pronounced as the letters “U” and “N” instead of as “un,” is not an acronym, but UNICEF is, since it is pronounced as a single word. Periods are generally omitted in acronyms. Here are some examples of organization names turned into acronyms.
- NATO: North Atlantic Treaty Organization
- NASA: National Aeronautics and Space Administration
- SAARC: South Asian Association for Regional Cooperation
- OPEC: Organization of the Petroleum Exporting Countries
- CERN: Conseil Européen pour la Recherche Nucléaire (European Council for Nuclear Research)
Computerese has many of its own acronyms.
- ASCII: American Standard Code for Information Interchange
- CAD: computer-aided design
- DOS: disk operating system
- LAN: local area network
Business jargon, of course, isn’t far behind.
- EBITDA: earnings before interest, tax, depreciation, and amortization
- LIBOR: London interbank offer rate
- NOPAT: net operating profit after tax
- FTSE (pronounced FOOT-see): Financial Times Stock Exchange
Interestingly, some terms start life as acronyms but then, through frequent usage, become words in their own right.
- laser: light amplification by stimulated emission of radiation
- radar: radio detection and ranging
- sonar: sound navigation and ranging
- scuba: self-contained underwater breathing apparatus
You might find the origins of the words fubar and snafu unexpectedly interesting.
Over time, acronyms that are five letters or longer often lose their capitalization. Those that are derived from proper nouns retain the initial capital letter.
- Benelux: Belgium, the Netherlands, Luxembourg
- Unesco: United Nations Educational, Scientific and Cultural Organization
- Interpol: International Criminal Police Organization
Categories of abbreviations are fluid and can overlap. For instance, some people may pronounce the individual letters of AWOL and ASAP (initialisms), while others may pronounce these very same abbreviations as words (acronyms). Then also, you may discover a mix of initialism and acronym within a single abbreviation (e.g., JSON, JPEG, VLAN).
In everyday usage, the words acronym and abbreviation are often used interchangeably. As an editor or writer, it is still useful to maintain the traditional distinction between the two, as discussed in this article on acronyms versus other abbreviations, since usage rules for acronyms and initialisms can differ based on the style you follow.
Contractions, shortened forms
A contraction is the shortened form of a word, in which some letters are omitted. A period is generally placed at the end to indicate that the word is contracted. When read aloud, a contraction is pronounced the same as the original word.
- Dr.: Doctor
pronounced “doctor”
- Mr.: Mister
- Jr.: Junior
- Ltd.: Limited
- Asst.: Assistant
- Sgt.: Sergeant
- hr.: hour
- yr.: year
Ms. is not a contraction, although it is written like one. It is merely the combination of Miss and Mrs., created in the 1950s as a neutral alternative that doesn’t signify a woman’s marital status.
Sometimes, an abbreviation is simply a shortened form, retaining only the first syllable or the first few letters of a word. The shortened form is pronounced the same as the original word.
- Rev.: Reverend
read aloud as “reverend,” not “rev”
- Pres.: President
- Gen.: General
- Sen.: Senator
- Inc.: Incorporated
- Corp.: Corporation/Corporal
- min.: minute/minimum
- sec.: second
Contractions and other shortened forms are often used in academic writing, especially in appendixes and reference lists.
- abbr.: abbreviation
- Prof.: Professor
- etc.: et cetera, which means “and so forth”
- et al.: et alii or et aliae, meaning “and others”
- ibid.: ibidem, or “in the same place” (used while repeating a source in a reference list)
- vol.: volume
- ed.: editor/edition
- trans.: translator
With et al., which is the abbreviated form of the Latin phrase et alii or et aliae (“and others”), be careful to not use a period after et.
- Incorrect:Remy et. al., 1993
- Correct:Remy et al., 1993
With frequent usage, some shortened forms eventually become words in their own right, and then no longer take a period at the end.
- lab (laboratory)
- ref (referee)
- temp (temporary employee)
- vet (veteran/veterinarian)
- ad (advertisement)
- gym (gymnasium)
Use of periods
Periods are generally omitted in acronyms and initialisms with capital letters.
- CEO
- USA
- ATM
- SSN
- NATO
- SAARC
- NAFTA
- DVD
Periods are often used in initialisms with lowercase letters.
- e.g.
- i.e.
- p.m.
But don’t use periods in abbreviated SI units of measurement.
- 10 cm (not 10 c.m.)
- 46 kg (not 46 kg.)
- 10 g (not 10 g.)
Abbreviated SI units don’t have a separate plural form: 10 cm, not 10 cms for “10 centimeters.”
Periods are also omitted in technical and scientific abbreviations and those that include the word per.
- mph: miles per hour
- ppm: parts per million
- rpm: revolutions per minute
- bhp: brake horsepower
- fp: freezing point
Periods generally mark a contraction or other shortened form in American usage.
- Dr.
- Mr.
- Rev.
- Sen.
- Jan.
- Inc.
- ed.
- vol.
But in British usage, periods are used only in shortened forms that comprise the first few letters of a word. Otherwise, the period is omitted.
- Jan., Sun., Rev., Prof.
butMr, Dr, Mrs, Jr, Sr, Ltd
For a full discussion, see Periods in Acronyms and Abbreviations.