Constituent (linguistics) facts for kids

In grammar, a constituent is a word or a group of words that works together as one unit. Think of it like a building block in a sentence. When we look at how sentences are built, we break them down into these smaller parts.

This idea of "constituents" is mostly used in phrase structure grammar, which is a way of understanding how sentences are put together. Even other types of grammar, like dependency grammar, also see sentences as having these smaller parts.

We use special tests called constituency tests to find these building blocks. These tests help us figure out which words stick together to form a unit. Many constituents are phrases. A phrase is a group of two or more words that have a main word (called a head) and work together as a single part of the sentence. If a group of words passes one or more of these tests, it's likely a constituent.

Finding Constituents: Special Tests

Constituency tests are like tools that help us find the different parts of a sentence. There are many tests we can use for English sentences. Here are some common ones:

• Topicalization (moving to the front)
• Clefting (using "It is/was...")
• Pseudoclefting (using "what is/are...")
• Pro-form substitution (replacing with a pronoun)
• Answer ellipsis (answering a question)
• Passivization (changing active to passive voice)
• Omission (leaving words out)
• Coordination (joining with "and")

These tests are helpful, but they aren't always perfect. Sometimes, a group of words might pass one test but not another. It's best to try several tests to be sure if a group of words is a constituent.

Topicalization (Moving to the Front)

This test involves moving a group of words to the very beginning of a sentence. If the sentence still makes sense, that group of words is likely a constituent.

• Original: He is going to attend another course to improve his English.
• Test: To improve his English, he is going to attend another course.

Since the second sentence sounds natural, "to improve his English" is a constituent.

Clefting (Using "It is/was")

Clefting means putting a group of words (let's call it X) into a special sentence structure that starts with "It is/was X that...".

• Original: She bought a pair of gloves with silk embroidery.
• Test: It was a pair of gloves with silk embroidery that she bought.

This works, so "a pair of gloves with silk embroidery" is a constituent.

Pseudoclefting (Using "What is/are")

Pseudoclefting is similar to clefting. It puts emphasis on a phrase by placing it before "is/are what" or "is/are who."

• Original: She bought a pair of gloves with silk embroidery.
• Test: A pair of gloves with silk embroidery is what she bought.

This also works, showing that "a pair of gloves with silk embroidery" is a constituent.

Pro-form Substitution (Replacing with a Pronoun)

This test involves replacing a group of words with a pro-form (like a pronoun such as it, he, there). If the sentence remains grammatically correct and its meaning doesn't change too much, the original group of words is a constituent.

• Original: I don't know the man who is sleeping in the car.
• Test 1: *I don't know him who is sleeping in the car. (This sounds wrong.)
• Test 2: I don't know him. (This sounds correct.)

The fact that the second test works shows that "the man who is sleeping in the car" acts as one unit, or constituent.

Answer Ellipsis (Answering a Question)

This test checks if a group of words can stand alone as a complete answer to a question.

• Question: What did you do yesterday?
• Answer 1: Worked on my new project. (This is a good answer.)
• Answer 2: *Worked on. (This doesn't make sense as a full answer.)

Since "Worked on my new project" can be a full answer, it's a constituent. "Worked on" is not.

Passivization (Changing Voice)

Passivization means changing a sentence from active voice to passive voice, or vice versa. In this change, the object of the active sentence becomes the subject of the passive sentence.

• Active: A car driving too fast nearly hit the little dog.
• Passive: The little dog was nearly hit by a car driving too fast.

Since both "A car driving too fast" and "the little dog" could be moved and the sentence still made sense, they are constituents.

Omission (Leaving Words Out)

This test checks if you can remove a group of words without making the sentence ungrammatical. Often, words that tell you when or where something happened can be removed.

• Original: Fred relaxes at night on his couch.
• Test 1: Fred relaxes on his couch. (Still makes sense.)
• Test 2: Fred relaxes at night. (Still makes sense.)

Because "at night" and "on his couch" can be removed, they are constituents.

Coordination (Joining with "And")

The coordination test suggests that only constituents can be joined together using words like "and," "but," or "or."

• Example: He enjoys [writing sentences] and [reading them].

Here, "writing sentences" and "reading them" are joined by "and," which means they are likely constituents. However, this test can sometimes be tricky and isn't always as reliable as others.

Constituency Tests and Clearing Up Confusion

Sometimes, a sentence can have more than one meaning because of how its parts are grouped. This is called syntactic ambiguity. Constituency tests can help us figure out which meaning is intended.

Let's look at the sentence: They killed the man with a gun.

This sentence can mean two different things:

1. 'The man was shot with a gun.' (The gun was the tool used to kill him.)
2. 'The man who was killed had a gun with him.' (The gun belonged to the man.)

The different meanings come from how we group the words:

• Meaning 1: They killed [the man] [with a gun]. (Here, "with a gun" is a separate unit, telling us how they killed him.)
• Meaning 2: They killed [the man with a gun]. (Here, "the man with a gun" is one unit, describing the man.)

We can use the answer ellipsis test to show this:

• To check Meaning 1 (gun as instrument):

* Question: How did they kill the man? * Answer: With a gun. (This works, so "with a gun" can be a separate constituent.)

• To check Meaning 2 (man had a gun):

* Question: Who(m) did they kill? * Answer: The man with a gun. (This works, so "the man with a gun" can be a single constituent.)

This picture shows how words can be grouped in different ways.

These tests help us understand how sentences are built and can even help us understand the different meanings a sentence might have. Most grammarians use these tests to figure out the structure of sentences.

Images for kids

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  Two potential analyses of constituent structure

See also

In Spanish: Constituyente sintáctico para niños