What Is An Indefinite Article? Definition & Examples

Would you like a cookie? How about an orange? Or maybe an ice cream scoop with a cherry on top? Unfortunately, snack time will have to wait, because we need to learn about articles. We use articles to point out that a noun is a noun, and all of our tasty sentences used a type of article called an indefinite article. If you’re a bit peckish, grab a snack before you join us in chowing down on a buffet of helpful information about indefinite articles.

What is an indefinite article?

An article is a word that typically identifies a part of a speech as a noun (or noun equivalent) without describing it. An indefinite article is an article that refers to a noun without specifying it or refers to a noun to introduce it for the first time. For example, the sentence I saw a dog at the park uses the indefinite article a. The article a precedes the noun dog, but doesn’t specify which kind of dog it is or provide any other details about it.

In English, there are two indefinite articles: a and an. In general, the word a is used before a word that begins with a consonant and an is used before a word that begins with a vowel. For example:

• She found a penny on the ground. (P is a consonant.)
• He ate an apple. (A is a vowel.)

Articles, including a and an, act like adjectives in that they only modify nouns or words and phrases acting as nouns. Articles always come before any other modifiers, such as adjectives or adverbs. For example:

❌ Incorrect: She dressed up as really spooky a ghost for Halloween.
✅ Correct: She dressed up as a really spooky ghost for Halloween.

It’s important to remember that you will use a or an depending on the word that immediately follows the article, which might not be the noun that it modifies. For example,

• Kyle is a boy.
• Kyle is an energetic boy.

Typically, it is considered grammatically incorrect to use either a or an before plural words:

❌ Incorrect: They built a sandcastles.
✅ Correct: They built a sandcastle.

❌ Incorrect: I ate an apples.
✅ Correct: I ate an apple.

Indefinite article examples

In English, the two indefinite articles are a and an.

Indefinite articles in a sentence

The following sentences show examples of how we use a and an. You will notice that which article we use is determined by the word that comes immediately after it.

• A monkey stole my peanuts.
• We saw an airplane fly across the sky.
• The sushi chef prepared meals for a hungry crowd.
• It was an early morning for me.

How about definite articles? Refresh your memory on the everything there is to know about them.

What is the role of indefinite articles?

A and an are very common words that appear in many sentences. Let’s look at two major roles that indefinite articles can fill.

Introduce a noun

On the first mention of a noun, we often use indefinite articles to introduce it to a reader or listener. Once it is introduced, we can then use the definite article the to indicate we are referring to that specific thing. For example:

• I took a book off of the shelf. The book was pretty heavy.
• We saw a flock of birds. The birds were looking for food.

Refer to nonspecific things

Sometimes, we want to refer to something without specifying it. For example, it might be unimportant or unnecessary to give exact details about something. In this case, we can use a or an to refer to the noun. For example:

• My daughter wants a puppy. I think I’ll get her one because a puppy would make a good friend. (The specifics of the puppy don’t matter because the speaker is referring to a puppy that they don’t actually have yet.)
• Matt is a firefighter. He has worked as a firefighter for many years. (Matt is just one of the many firefighters of the world. The specifics of his job are unimportant so the indefinite article a is used.)

Indefinite article exceptions & best practices

Using a and an isn’t too tough most of the time. However, there are a few things to watch out for.

Consonant and vowel sounds

In general, the word a is used before consonants and an is used before vowels. However, another rule overrides this general practice. If a word begins with a consonant sound or a vowel sound, the sound will take priority over whatever the first letter is.  For example:

• He drew an oval. (Oval begins with a vowel sound.)
• She is a one-woman army. (One begins with a consonant sound. When said aloud, one sounds like it begins with a W.)
• Dennis bought a hamburger. (Hamburger begins with a consonant sound.)
• Jess waited for an hour. (Hour begins with a vowel sound. The letter H is not pronounced in hour, so it sounds like it begins with an O.)

Some more examples of words that can be tricky include:

• university, uniform, useless, European (These words begin with a Y consonant sound and pair with a.)
• honor, honest, heir (These words have a silent H and pair with an.)

Plural and uncountable nouns

As mentioned earlier, a and an are not typically used before plural nouns. Plural nouns will either use the definite article the or no article at all:

✅ Correct: Ingrid bought the apples. Ingrid bought apples.
❌ Incorrect: Ingrid bought an apples.

Typically, indefinite articles are also not used with uncountable nouns even though uncountable nouns are usually treated as singular nouns. If you need help understanding uncountable nouns, we have a handy guide about them for you.

❌ Incorrect: The cup was filled with a milk.
✅ Correct: The cup was filled with milk.

❌ Incorrect: The power plant produces an electricity.
✅ Correct: The power plant produces electricity.

Write smarter with Grammar Coach™

You’ll never mistake definite and indefinite articles again when you check your writing Thesaurus.com’s Grammar Coach™. This writing tool uses machine learning technology uniquely designed to catch grammar and spelling errors. Its Synonym Swap will find the best nouns, adjectives, and more to help say what you really mean, guiding you toward clearer, stronger, writing. Perfect grammar has never been easier.