A brief guide to using ‘a’ and ‘an’

The broad rules many teach for indefinite articles—that ‘a’ should go before a consonant and ‘an’ before a vowel—aren’t entirely accurate.

Determining whether to use “a” versus “an” should not be confusing, but it is.

This week, I had a prolonged discussion with a co-worker about why “an MRI” is correct and “a MRI” is not.

It turns out that many of us were taught the wrong rules for use of the indefinite articles. I remember being told to use “an” when the word preceding it starts with a vowel and to use “a” when the word preceding it starts with a consonant.

The rules actually say to use “an” before any word beginning with a vowel sound and to use “a” before any word beginning with a consonant sound. No matter how the word is spelled, “a” comes before words with a consonant sound, including /y/,/h/, and /w/. Likewise, no matter how it’s spelled, “an” comes before a word with a vowel sound.

Take these examples:

  • a unicorn
  • a user experience study
  • an umbrella
  • an uprising
  • a hotel
  • a historical study
  • an heir
  • an honor

Here are a couple of example sentences:

“It was quite a sight to watch such a histrionic performance.”
“That is an ugly drawing of a ukulele.”

All of this gets tricky when it comes to abbreviations, symbols, or numbers. But the rule is the same; it depends on how the term is pronounced.

  • a URL
  • a AAA membership
  • an FAQ list
  • an MRI
  • an NCAA player
  • an @ sign
  • a #
  • an 800 number
  • a 90s party

Another example sentence:

“I need a URL in order to create an FAQ page.”

So remember: Cut the confusion and answer the question of “a” versus “an” by listening instead of looking.

Download this free white paper to discover 10 ways to improve your writing today.

Ragan.com readers, any “a” versus “an” stories to share?

Laura Hale Brockway is medical writer based in Austin, Texas. She is also a regular contributor to PR Daily. Read more of her work at impertinentremarks.com.

COMMENT

Ragan.com Daily Headlines

Sign up to receive the latest articles from Ragan.com directly in your inbox.