Acronym vs. Initialism: Types of Abbreviations

Summary

Abbreviations may be acronyms, initialisms, contractions, or just shortened forms of words.

  • An acronym is an abbreviation pronounced as a single word.

    Examples
    • NATO, NASA, UNICEF, GIF, LAN, DOS, EBITDA, ANOVA, laser
  • In an initialism, each letter is individually pronounced.

    Examples
    • USA, UK, EU, UN, PDF, PC, ATM, SSN, MBA
  • In contractions, some letters are omitted to make the word shorter. A shortened form may even contain only the first letters or syllable of a word.

    Examples
    • Dr., Mr., Mrs., Jr., Ltd., Asst.
    • Rev., Sen., Inc., Jan., Prof.

While all acronyms are abbreviations, only abbreviations pronounced as words are acronyms (NAFTA and NASA, but not USA or UK). Omit the article the before an acronym even if it would be used with the full form.

Example
  • Anita works at the NASA.

But use the as usual with initialisms (in which the letters are individually pronounced).

Example
  • Lulu lives in the UK.

What is an abbreviation?

An abbreviation is the shortened form of a term, often formed using the first letters of a multi-word phrase. It can also simply be the contracted or shortened form of a word.

Examples
  • USA: United States of America
  • PC: personal computer
  • NATO: North Atlantic Treaty Organization
  • CEO: chief executive officer
  • DNA: deoxyribonucleic acid
  • ANOVA: analysis of variance
  • Dr.: doctor
  • Mt.: mount
  • Jan.: January
  • Inc.: incorporated
  • abbr.: abbreviation
  • Eng.: English

Types of abbreviations

An abbreviation may be an acronym, an initialism, a contraction, or another shortened form.

Types
  • Acronym: Pronounced as a word
    NASA, NAFTA, BAFTA, NATO, LAN, laser, scuba
  • Initialism: Individual letters pronounced
    UK, USA, ATM, UN, FYI, a.m.
  • 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.

In this article, we discuss the different types of abbreviations and how to use them correctly.

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.

Examples
  • 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.

Examples
  • 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.

Examples
  • 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.

Examples
  • 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.

Examples
  • 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.

Examples
  • 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.

Examples
  • mph: miles per hour
  • ppm: parts per million
  • ac: alternating current
  • dc: direct current
Tip

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.)

Examples
  • 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.

Examples
  • 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.

Examples
  • 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.

Examples
  • 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.

Examples
  • 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.

Examples
  • Benelux: Belgium, the Netherlands, Luxembourg
  • Unesco: United Nations Educational, Scientific and Cultural Organization
  • Interpol: International Criminal Police Organization
Tip

All acronyms are abbreviations, but not all abbreviations are acronyms. While NASA and UNICEF are acronyms because they are pronounced as words, USA and UN are initialisms since their letters are pronounced individually.

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).

It is still useful to distinguish between the two: acronyms can be used at the start of a sentence, while initialisms generally are not, and use of the article the differs between the two, as discussed below.

Acronyms at start of sentence

In formal writing, abbreviations are not used at the start of a sentence. You must rephrase or use the full form instead.

Examples
  • Poor: UN officials from around the world have arrived in Vienna for a conference.
  • Better: United Nations officials from around the world have arrived in Vienna for a conference.

But acronyms are acceptable in this position since they are pronounced as words.

Example
  • Acceptable: NATO officials have arrived in Brussels for a conference today.

Use of the with acronyms

The article the is generally omitted before an acronym of a proper noun, like the name of an organization (e.g., NASA, NATO, OPEC).

Examples
  • The NASA runs the U.S. civil space program.
  • The NATO constitutes a system of collective defense.
  • The UNESCO is a UN agency based in Paris.
  • The OPEC was founded in 1960 in Baghdad.

With the full form, use the as appropriate.

Examples
  • The National Aeronautics and Space Administration runs the U.S. civil space program.
  • The North Atlantic Treaty Organization is an intergovernmental military alliance.
  • The United Nations Educational, Scientific and Cultural Organisation was founded in 1945.
  • The Organization of the Petroleum Exporting Countries is headquartered in Vienna.

In contrast, initialisms retain the use of the article the.

Examples
  • The UN is a global organization.
  • The BBC is a British broadcaster.
  • Maya lives in the UK now.

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.

Examples
  • Dr.: Doctor
    pronounced “doctor”
  • Mr.: Mister
  • Jr.: Junior
  • Ltd.: Limited
  • Asst.: Assistant
  • Sgt.: Sergeant
  • hr.: hour
  • yr.: year

It’s fine to start a sentence with a contraction.

Examples
  • Dr. Minerva Dash is our new cardiologist.
  • Mr. Jones will call you tomorrow.
Tip

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.

Words like you’re, don’t, and ma’am are also contractions, but they are not generally classified as abbreviations.

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.

Examples
  • 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.

Examples
  • 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
Caution

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.

Examples
  • 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.

Examples
  • 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.

Examples
  • CEO
  • USA
  • ATM
  • SSN
  • NATO
  • SAARC
  • NAFTA
  • DVD

Periods are often used in initialisms with lowercase letters.

Examples
  • e.g.
  • i.e.
  • p.m.

But don’t use periods in abbreviated SI units of measurement.

Examples
  • 10 cm (not 10 c.m.)
  • 46 kg (not 46 kg.)
  • 10 g (not 10 g.)
Tip

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.

Examples
  • 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.

Examples
  • 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.

Example
  • Jan., Sun., Rev., Prof.
    but
    Mr, Dr, Mrs, Jr, Sr, Ltd

For a full discussion, see Periods in Abbreviations and Acronyms.

Usage guide

The abbreviations you use can be acronyms, initialisms, contractions, or just shortened forms of words. An acronym is pronounced as a single word (e.g., NATO, GIF), while in an initialism, each letter is individually pronounced (e.g., USA, PDF). Contractions such as Dr. and Mrs. are also abbreviations, as are shortened forms like Rev. and Sen. While all acronyms are abbreviations, only abbreviations pronounced as words are acronyms (NATO and NASA, but not EU or UK). Although abbreviations are generally not used to start a sentence in formal writing, using acronyms is acceptable in this position, since they are pronounced as words.

Quick Quiz

Which of these is an initialism?
Choose from these answers
All done!
Which of these is an acronym?
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Which of these are abbreviations?
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Which of these are acronyms?
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Which is preferred?
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Which is preferred?
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All done!

Did You Know?

In questions, the verb must agree with the inverted subject (Where is/are my keys?).
Know more:Rules of Subject-Verb Agreement