ini·​tial·​ism | \ i-ˈni-shə-ˌli-zəm How to pronounce initialism (audio) \

Definition of initialism

: an abbreviation formed from initial letters

Keep scrolling for more

What is the difference between the words acronym and initialism?

Acronym is a fairly recent word, dating from the 1940s, although acronyms existed long before we gave them that name. The term was preceded in English by the word initialism, meaning an abbreviation formed from the initial letters of a phrase, and which has been in use since the late 19th century.

Some people feel strongly that acronym should only be used for terms like NATO, which is pronounced as a single word, and that initialism should be used if the individual letters are all pronounced distinctly, as with FBI. Our research shows that acronym is commonly used to refer to both types of abbreviations.

Examples of initialism in a Sentence

Recent Examples on the Web With the posting of the original image to Instagram, captioned with the simple and chic initialism DTMH, Solange was one of many who called out a publication for false representation. Kate Branch, Vogue, "10 Times Beauty Got Political in 2017," 21 Dec. 2017 At the time of Lord Fisher’s letter, at the close of World War I, Britain must have seemed awash in initialisms. WSJ, "OMG! It Started in 1917 With a Letter to Churchill," 8 Sep. 2017 Playing with these initialisms didn’t end with Lord Fisher. WSJ, "OMG! It Started in 1917 With a Letter to Churchill," 8 Sep. 2017 The question is just how abbreviated should this initialism be? Bill Daley,, "Why LGBT initialism keeps growing," 2 June 2017

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'initialism.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

See More

First Known Use of initialism

1844, in the meaning defined above

Keep scrolling for more

Learn More about initialism

Time Traveler for initialism

Time Traveler

The first known use of initialism was in 1844

See more words from the same year

Statistics for initialism

Cite this Entry

“Initialism.” Dictionary, Merriam-Webster, Accessed 26 Feb. 2020.

More from Merriam-Webster on initialism

Rhyming Dictionary: Words that rhyme with initialism Encyclopedia article about initialism

Comments on initialism

What made you want to look up initialism? Please tell us where you read or heard it (including the quote, if possible).


See Definitions and Examples »

Get Word of the Day daily email!

Test Your Vocabulary

More Confusing Words—Quiz

  • cats on impossible timber
  • The magician ______ moved the selected card to the top of the deck.
Spell It

Can you spell these 10 commonly misspelled words?

Dictionary Devil

Test Your Knowledge - and learn some interesting things along the way.

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!