Most of us know the rule about putting “a” before words that start with consonants and “an” in front of words that start with vowels but as it turns out, it’s actually more complicated than that. For example, here’s a question from a student:
I’m wondering if it is actually “a hour” or “an hour.” “An hour” sounds like it’s correct, but “a hour” looks more correct to me when written. I’m just curious which one it should be.
The rule is that you use “an” in front of words that start with a vowel sound and “a” before words beginning with a consonant sound.
Do I use ‘A’ or ‘An’?
So to answer the question above, “an hour” is correct, because the word “hour” starts with a vowel sound. People frequently ask about words that start with the letters U or H because sometimes these words start with vowel sounds and other times they start with consonant sounds. Here is another example. It is “a heartfelt goodbye” because “heartfelt” starts with an H sound, but it is “an honorable person” because “honorable” starts with an O sound. Similarly, it is “a urology appointment,” but “an understandable nervous feeling” you have when going to that appointment.
The letters O and M can be a little confusing too. Usually, you’ll put “an” before words that start with O, but sometimes you actually use A. For instance, you’d use A if you were to say, “She has a one-time opportunity,” because “one-time” starts with a W sound. You would then say “an opportunity” because “opportunity” begins with a vowel sound. Similarly, you would say, “She has an MBA, but works as a midwife,” because “MBA” begins with a vowel sound and “midwife” begins with a consonant sound.
You must use “a” before words that start with consonant sounds and “an” before words starting with vowel sounds.
There are other letters that can sometimes be pronounced either way also. Try to remember that it’s the sound that determines whether you use “a” or “an”, and not the first letter of the word.
Complications can arise because some words are pronounced differently in British English and American English. For instance, the word for a certain type of plant is pronounced “erb” in the American version of English and “herb” in the British version of English. So the proper format in the USA is “an herb,” and the proper form in England is “a herb.” In the rare case where this presents a problem, write the form that is used where you live or by the majority of your readers.
‘A Historic’ or ‘an Historic’?
Since we’re speaking about pronunciations, let’s talk about “a historic.” Some American citizens will argue that it should be “an historic,” and one of the most controversial interactions I had at a book signing was over this. In the end, I settled firmly with the side that says it should be “a historic event.”
Here’s why: Most people pronounce the H in “historic,” and there’s nothing terribly unique about the word. So if it starts with a consonant sound—a hard H sound—it will get an “a” in front of it like every other word that start with a consonant sound.
In some areas of the world, people don’t pronounce the H. Linguists call this an unvoiced H. Back in high school, I had a teacher who was born Boston who would say “istoric” instead of “historic. (For him, it was also “uman” rather than “human”)
So if you grew up in a region where everyone says “istoric,” it’s reasonable to assume that it should be “an istoric” because to you, the word starts with a vowel sound. But, that’s not the standard or common pronunciation in most parts of the world, so unless you’re writing for a regional publication and your readers call things “istoric,” it’s not the right choice.
If you’re feeling argumentative about this point, I suggest you look at This Website, ‘The Slot’. Washington Post copy editor, Bill Walsh, writes an exhaustive review of how different style guides manage this word. But you should know however that after reviewing many style guides, he too firmly believed in “a historic” being the correct choice.
Related: We have a whole article dedicated to the debate of ‘a history’ vs ‘an historic’.
Definite and Indefinite Articles
“An” and “a” are referred to as indefinite articles, and “the” is referred to as a definite article. The one difference is that “a” and “an” don’t say anything particularly unique about the words that follow. For instance, think about the sentence, “I need a candy bar.” You’ll be happy with any candy bar—just a candy bar is fine. But if you say, “I need the candy bar,” then you want a specific candy bar. There must be something unique about the one, specific candy bar you are asking for. That’s why “the” is called a definite article—you’re wanting something definite. That is at least what helps me to remember the name.
It’s the sound of the next word, not the first letter of the next word, that decides whether you want “an” or “a.” Consonant sounds call for an “a,” and a vowel sound will call for an “an.”