The Indefinite Article | Parts of Speech | Grammar | Khan Academy

Hello grammarians! We've talked a little about the difference between these special adjectives, a and an, and the also known as the articles. I want to go a little deeper.

Now, we know that "the" is the definite article and "a" or "an" is the indefinite, right? If you're being non-specific in language, you'd use an indefinite article, as in, "May I have an orange?" If you want to talk about one orange in particular, you'd use the definite article: "May I have the orange?"

Now, into this framework, I'd like to introduce a complication into that indefinite article—something to chew on, something to think about. You'll notice I said the indefinite article is "a" or "an." What's with that "or"? When do we use "a" and when do we use "an"?

And the answer to that question comes down to one thing, and one thing only: the next sound to come out of your mouth. Let us take, for example, two apes: the orangutan and the bonobo. "Orangutan" starts with "o"; "bonobo" starts with "b." Marvelous great apes, cousins to humans—treat them with love and respect!

When you say a word that begins with a consonant, which is to say any sound that you make when your lips or your teeth or your tongue are touching, you say "a." "A bonobo"—the "b" sound requires my lips to come together and then pop apart.

When you say a word that begins with a vowel sound, which is any sound that you make with an open mouth and no teeth, lips, or tonguey business, you say "an." "An orangutan"—"orangutan" starts with an "o" sound. Little vocal warm-up so you can see how this is going to break down, right?

Whatever sound comes after the indefinite article is going to determine the shape the indefinite article takes. "A pencil," "an open door," "a zebra," "an extra pudding cup," "a sailboat," "an NBA player," "a unicorn."

Wait! Well, hold up! Do you notice something weird about those last two examples? "NBA player"—well, that begins with "n," doesn't it? And "unicorn" begins with "u," so why isn't it "a NBA player" and "an unicorn"?

Because—and this is the crucial, complicated, confusing part—it's not about the letter that the word begins with in spelling. It's about the sound that letter makes. So, "NBA" doesn't begin with the "nuh" sound; it's not "na ba," it's "n ba." And "unicorn" doesn't begin with an "uh" or an "oo" sound; it begins with "ya." "You unicorn."

It's not about the letter, it's about the sound! "E" in "NBA" is a vowel sound, so it's "an NBA player," and "ya" in "unicorn" is a consonant sound. Notice how you lift your tongue as you practice the difference between "unicorn" and "unicorn."

So, it's a consonant sound: "it's a unicorn." Same deal with words that begin with silent "h," like "herb," "heirloom," or "hour." "An hour had passed." "Ow, I'm going to start an herb garden." "Er, that cuckoo clock is an heirloom."

Why does this happen? What's the difference between "a" and "an"? The "nuh" sound in "an" helps separate sounds. Here, listen to this incorrect example: "For my snack today, I ate a apple." Sounds weird, right? One right after the other: "ah."

Now listen to this: "For my snack today, I ate an apple." The "nuh" in "an" is kind of like a springboard from one vowel sound into the next: "ah napol." And that's what I want you to take away from this lesson because it can be very confusing and, well, indefinite.

But think about the sound that the word makes, not the letter that it begins with: "an orangutan," "a bonobo," "an NBA player," "a unicorn." "A you can learn anything."

Dave it out!