HTML, EU, and NATO are examples of acronyms. Merriam-Webster defines acronyms as words “formed from the initial letter or letters of each of the successive parts or major parts of a compound term”.
In some expressions, acronyms can be preceded by an indefinite article (a or an). But how do you choose the right indefinite article before acronyms?
The rule for indefinite articles before acronyms: an before vowel sound, a before consonant sound
Acronyms can be read as pronounceable words (for example, NASCAR) or as a series of letters (for example, BBC). It’s important to know how to pronounce an acronym, because the rule for choosing the right indefinite article before acronyms is based on pronunciation, not spelling.
If the acronym begins with a vowel sound, use the indefinite article an before the acronym.
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- an MPEG file (not a MPEG file)
- an HIV patient
- an HTML file
- an LED lamp
- an MBA degree
- an EU member (but a European Union member)
- an EU project
If the acronym begins with a consonant sound, use the indefinite article a before the acronym.
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- a NATO member
- a UNESCO volunteer
If an acronym has more than one pronunciation, choose the one your target reader prefers. If you are not sure how your target reader pronounces a word, choose the first pronunciation listed in the dictionary.
- a FAQ page (if you pronounce FAQ as a word) or an FAQ page (if you pronounce FAQ as an initialism, so letter by letter)
Sometimes you need indefinite article a before a vowel and an before a consonant
The choice of a or an before an acronym is determined by the way the acronym sounds, and not by its first letter.
So, you can find the indefinite article a before acronyms that begin with a vowel (for example, a UN delegation). And you can find the indefinite article an before an acronym that begins with a consonant (for example, an MS Word manuscript).
Listen to the sound of acronyms to choose the right indefinite article
Acronyms are rarely preceded by a or an, except when used adjectivally, says the Chicago Manual of Style. If you have to use an acronym with an indefinite article, the way an acronym is read aloud determines which indefinite article precedes it. In summary, use an before acronyms beginning with a vowel sound. Use a before acronyms beginning with a consonant sound.
Acknowledgments: I’m grateful to Brion. S. and Jérôme B. for helping me improve this article.
Do you need to hire a freelance editor? Send me a message at editor@languageediting.com.
Related posts:
- Is it acceptable to use many abbreviations in a research paper?
- What’s the plural of euro? Euro or euros?
- Is “et al.” singular or plural?
Last revised on 19 July 2022
