Restrictive Modifier

What Is a Restrictive Modifier?

A restrictive modifier is a word, phrase, or clause that defines another element. A restrictive modifier is essential for meaning. If a restrictive modifier were to be removed, readers would be left with a question like "Which one are we talking about?". Unlike additional information in a sentence (which can be offset with commas or some other parenthetical punctuation like dashes), a restrictive modifier is not offset with any punctuation, and this signifies it is essential to the meaning.

There is one notable exception to this. If a restrictive modifier is a phrase or clause that starts a sentence, it can be separated from the thing it modifies with a comma. (More on this below.)

Defining and Non-defining Modifiers

Restrictive modifiers are often called "defining modifiers," and non-restrictive modifiers are often called "non-defining" modifiers. These terms are more intuitive because defining a word is a clearer idea than restricting a word.

Examples of Restrictive Modifiers

Here are some examples of restrictive modifiers (shaded):

• The girl who stole the bread is back.
• The horse that led the way for the whole race fell at the last fence.
• The ornament the dog chewed was worth more than my car.

In the examples above, the restrictive modifiers are all restrictive clauses functioning as adjectives. Notice how they are not offset with commas. The shaded text is essential to the meaning of the sentence. Look at these two examples:

• My brother who lives in London is visiting on Saturday.
(This is a restrictive modifier. It is essential information to identify which of my brothers.)
• My brother Mark, who lives in London, is visiting on Saturday.
(This is a non-restrictive modifier. We already know which of my brothers we're talking about. The text in bold is just additional information. That's why it's offset with commas.)

Adverbial Restrictive Modifiers and Other Types

Restrictive modifiers are not always adjective clauses, like those in the examples above. There are many other types. For example:

• My brother with a house in London is visiting on Saturday.
(This is a prepositional phrase functioning as a restrictive modifier (specifically, a restrictive adjectival phrase).)
• The pirate in the middle was planning a mutiny.
(This is another example of a prepositional phrase functioning as a restrictive modifier (specifically, a restrictive adjectival phrase).)

With modifiers that function as adjectives, it is relatively easy to see how the modifier defines its noun. Let's now look at some modifiers functioning as adverbs.

• Take the cake out of the oven when the alarm sounds.
(This is an adverbial clause functioning as a restrictive modifier (specifically, a restrictive adverb of time).)
• I'm leaving because it's raining.
(This is another example of an adverbial clause functioning as a restrictive modifier (specifically, a restrictive adverb of reason).)

With modifiers that function as adverbs, it is far more difficult to see how the modifier defines its verb. Nevertheless, the term "restrictive modifier" still applies to modifiers functioning as adverbs.

More importantly, notice that there are no commas. These are all restrictive (or defining) modifiers.

Remember that anything that modifies something else in a way that is essential for meaning is a restrictive modifier. So, the following are all restrictive modifiers:

• My vase
• The vase
• A vase
• The blue vase

However, when people talk about restrictive modifiers, they tend to have adjective clauses and adjective phrases in mind.

Why Restrictive Modifiers Are Important

Here are the two best reasons to care about restrictive modifiers.

(Reason 1) Know when to leave the commas out.

The meaning of your sentence will be affected by your decision on whether to use commas with an adjective clause. Both examples below are grammatically sound, but they have different meanings.

• My sister who is married won the lottery.
(This is a restrictive modifier. It specifies that I'm talking about my married sister, i.e., not a different sister.)
• My sister, who is married, won the lottery.
(This suggests I have just one sister. I've also told you that she is married, but I could have omitted that information. The bold text is a non-restrictive modifier.)

Remember that if your adjective clause is essential to identify its noun, then there are no commas. If it's just additional information, use commas, dashes, or parentheses (brackets)...or delete it.

Test for a Non-restrictive Clause

If you'd happily put it in parentheses (brackets) or delete it, use commas.

Read more about when to use a comma before "who" and "which."

(Reason 2) Use a comma if your modifier is fronted.

When the modifier is at the start of your sentence (known as "fronted"), offset it with a comma. For example:

• When the alarm sounds, take the cake out of the oven.
(This is a fronted adverbial clause.)
• At 2 o'clock, the third spirit appeared.
(This is a fronted adverbial phrase.)
• Famished from the journey, John decided to hunker down with his horse.
(This is a fronted adjective phrase.)

Read more about using commas to offset fronted modifiers. When the modifier is at the back (especially if it's an adverbial clause or phrase), don't use a comma.

• Take the cake out of the oven when the alarm sounds.
• The third spirit appeared at 2 o'clock.
(With post-positioned adverbial modifiers (i.e., ones at the back), don't use a comma. This is guidance that will keep you safe 99% of the time because the vast majority of adverbial modifiers are restrictive.)

Things get a little bit trickier with adjective phrases.

• John decided to hunker down with his horse, famished from the journey.
(This time, the comma is required otherwise we'd be talking about a horse that is famished from the journey. The comma distances the modifier from "horse.")

Read more about using commas before post-positioned modifiers (see Points 3 and 4).

Key Points