Constituent

Constituent Linguistics

Within linguistics, a constituent is a unit of language that exists within a larger sentence. Constituents are a vital part of syntax, and each constituent must follow the general rules of syntax. When we analyze the syntax of a sentence, we conduct a process called parsing, which involves breaking a sentence down into its constituents.

Fig 1. An example of parsing.

Every sentence contains constituents - they are the essential building blocks that make a sentence a sentence. Let's now take a closer look at the definition of constituent.

Constituent Definition

Constituents are the units of language that work together to build a sentence. They can be morphemes, phrases, and clauses (we'll look at examples of each of these shortly).

The vital constituents within a sentence are the subject and its predicate. A subject is who/what the sentence is about, and a predicate is the part of a sentence that adds detail or information to the subject (they usually contain a verb.)

Larger constituents can be further broken down into their own constituents.

This means that each sentence can contain multiple different constituents.

There are several 'tests' to help identify which phrases are constituents within a sentence. One example is testing which units of language can be replaced with a singular word.

In the above example, we can see that the noun phrase "The man with the old brown shoes" is a constituent, as all seven words can be replaced with the singular word he. We'll cover constituency tests in more detail later.

Constituent Types

As we mentioned, constituents can be morphemes, phrases, or clauses. The smaller constituents (e.g., morphemes) combine to form larger constituents (e.g., phrases), which can again combine to form larger constituents (e.g., clauses or predicates). Let's look at each of these with some examples.

Morphemes

Morphemes are the smallest unit of lexical units; they can be free (can stand alone) or bound (cannot stand alone). In simple terms, free morphemes are individual words that cannot be broken down further (e.g., cat, he, laptop, etc.), and bound morphemes are the affixes we attach to them (e.g., quickly, unfinished, houses, etc.).

Here, the free morpheme 'he' is the subject of the sentence and a valid constituent.

As bound morphemes cannot stand alone, they cannot be constituents on their own.

Phrases

Phrases are constituents that contain a group of words that act as a particular word class, i.e., a noun phrase works as a noun. Phrases can be categorized into noun phrases, verb phrases, prepositional phrases, adverb phrases, and adjective phrases.

Clauses

A clause is a constituent that contains a subject and a predicate. There are two types of clauses: independent and dependent. Independent clauses can stand alone, whereas dependent classes must be connected to independent clauses to get their meaning.

Now we have a good understanding of the elements of constituents, let's take a closer look at how they are structured.

Constituent Structure

The term constituent structure describes the grammatical structure of a sentence and how smaller constituents combine to form larger constituents.

For example, morphemes combine to form phrases, and phrases combine to form additional phrases and clauses. Additionally, each sentence will typically contain two main constituents: the subject and the predicate. Subjects are often nouns or noun phrases, and predicates are often verb phrases; however, this isn't always the case.

Immediate Constituent Analysis

The simplest way to illustrate constituent structure is by conducting an Immediate Constituent Analysis (aka IC analysis). Immediate Constituent Analysis is a form of parsing, a technique that involves breaking a sentence down into its constituents and presenting them in a tree diagram, like so:

Fig 2. Constituent Structure

Constituent Identification

Now we know all about constituents and their structure, let's look at some useful ways of identifying constituents within a sentence. One useful way to identify constituents is by conducting 'tests' (remember how at the beginning of the article we tried replacing whole phrases with a singular word? This was an example of a constituency test!)

Let's look at some more tests now.

Constituency Tests in Syntax

Formal constituency tests involve manipulating sentences, i.e., playing around with their order, to discover which groups of words are constituents. It's important to note that some tests work better for some sentences than others.

Sentence Fragment Answers

To conduct a sentence fragment test, restructure the sentence to form a question and an answer. Only constituents can be an appropriate answer while maintaining the same meaning.

Pro-form Substitution

The pro-form substitution test is the first test we saw in this article - it involves replacing a group of words with a pro-form word. If the words can successfully be replaced, they are a constituent.

Coordination

Only constituents can be joined to other constituents of the same kind (i.e., a noun phrase and a noun phrase) with the use of coordinating conjunctions. The coordinating conjunctions are For, And, Nor, But, Or, Yet, So,

Topicalization

The topicalization test involves moving the potential constituent to the beginning of the sentence and seeing if it still makes sense.

Clefting

Clefting involves placing the constituent within a frame and seeing if it still makes sense.

The frame is, "___ is/are + who/what/where/when/why/how."

It's important to remember that the same group of words may function as a constituent in one sentence but not in another. Syntax isn't just about the order of words, it's about the relationship between those words and the role they play within the sentence.

Constituent Example

It's time to put all of our new knowledge together. Let's take an example sentence and identify all of its constituents by conducting an Immediate Constituent Analysis and Sentence Fragment Answer and Topicalization tests.

Sentence = "The retired man grew potatoes in his garden."

First, identify the subject and the predicate - remember, subjects are usually noun phrases, and predicates are often verb phrases.

Let's now try a Sentence Fragment Answer test to see if we have grouped the correct words together into constituents.

Q: What did the retired man do?

A: Grew potatoes

Q: Where did the returned man grow potatoes?

A: in his garden

We can also apply the Topicalization test: