Acronym vs. Initialism: What’s the Difference?

Acronym is often used to describe any collection of first letters of words in a phrase: NASA for National Aeronautics and Space Administration, CEO for chief executive officer, and so on. But not all acronyms are really acronyms: Some are just initialisms. Here’s how to tell the two apart—and how abbreviations fit into the picture.

1. Acronym vs. Initialism
2. Acronym vs. Abbreviation

Acronym vs. Initialism

Before we get pedantic, though, let’s be clear: So many people consider acronym and initialism to be direct synonyms that dictionaries do list them as such, and it’s not “wrong” to use them interchangeably. But if you want to differentiate between the categories, it’s not hard to learn the distinction.

Basically, an acronym is any word formed by taking the first letters (or first parts of syllables) of each word in a phrase, title, or group of words—and then pronouncing that new word as a word. FOMO, for fear of missing out, is “FOH-moh.” BAFTA, for British Academy of Film and Television Arts, is “BAFF-tuh.”

For all the debate surrounding whether GIF (graphics interchange format) should be said with a soft or hard “g” sound, everybody can at least agree that it should be pronounced as a single-syllable word. Nobody says “G-I-F.” If we did, GIF wouldn’t be an acronym—it would be an initialism. 

Initialisms are terms made by taking each first letter in a phrase and then pronouncing each of those letters. Often, that’s because it’s not phonetically possible to pronounce a group of letters as a word—like TBD for to be determined or CNN for Cable News Network. But other times, we all seemingly decide it just sounds better or more appropriate to say the letters: CEO is “C-E-O,” not “SEE-oh,” and USA is “U-S-A,” not “OOH-sah.”

To make matters more complicated, certain terms are technically used as acronyms and initialisms. Take LOL. If you pronounce each letter individually, it’s an initialism. But people sometimes say it as a word—“LAWL” or “LOHL”—in which case it’s an acronym. The same goes for ASAP: “A-S-A-P” is an initialism, while “AY-sap” is an acronym.

And some acronyms have become so common that they’re widely written in lowercase, and you might not even realize they were acronyms to begin with. Laser, for example, stands for light amplification by stimulated emission of radiation, and snafu started out as military slang for situation normal: all fucked up.

Acronym vs. Abbreviation

Abbreviation is a catch-all term for any shortening of a word or phrase. This means that all acronyms and initialisms are abbreviations, but not all abbreviations are acronyms or initialisms.

Abbreviations include things like contractions (e.g. could’ve for could have, won’t for will not) and nicknames (Beth for Elizabeth, Alex for Alexander, etc.). It also includes words that have literally just been shortened. You might write mgmt instead of management, or assn for association. Cali is an abbreviation for California, and math (or maths, if you’re British) for mathematics. Abbreviations are all shortcuts, but there aren’t any overarching rules to create or pronounce them like there are with acronyms and initialisms.

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