Nonrestrictive Relative Clause

Glossary of Grammatical and Rhetorical Terms

Couple painting a wall red
The paint, which Mary bought at the hardware store, was bright red.  Frank and Helena / Getty Images

A nonrestrictive relative clause is a relative clause (also called an adjective clause) that provides added (though not essential) information to a sentence. Put another way, a nonrestrictive relative clause doesn't limit or restrict the noun or noun phrase it modifies. Also known as a non-defining relative clause.

In contrast to restrictive relative clauses, nonrestrictive relative clauses are usually marked by brief pauses in speech and are usually set off by commas in writing.

Examples and Observations

  • Nonrestrictive relative clauses . . . are usually set off by commas in writing, and you can usually detect 'comma intonation' in a speaker's voice
    The paint which Mary bought at the hardware store was bright red.
    The paint, which Mary bought at the hardware store, was bright red.
    The restrictive relative clause which Mary bought at the hardware store, limits which paint we're referring to, namely to paint which Mary bought at the hardware store. The nonrestrictive relative clause, on the other hand, does not restrict the reference of the noun paint; it is not information that distinguishes the paint from other paint. That Mary bought this paint at the hardware store is simply incidental information."
    (Kristin Denham and Anne Lobeck, Navigating English Grammar: A Guide to Analyzing Real Language. Wiley Blackwell, 2014)
  • Ms. Newmar, who lives next door, claims to be a Martian.
  • For a balloon to float, it must be filled with helium, which is lighter than the air around it.
  • "Besides the bookcase in the living room, which was always called 'the library,' there were the encyclopedia tables and dictionary stand under windows in our dining room."
    (Eudora Welty, One Writer's Beginnings. Harvard University Press, 1984)
  • "The United States, which presents itself as a global beacon of opportunity and prosperity, is quickly becoming a low-wage nation."
    (Saket Soni, "Low-Wage Nation." The Nation, January 20, 2014)
  • "Eugene Meyer, who was thirty-two years old, had been in business for himself for only a few years, but had already made several million dollars."
    (Katharine Graham, Personal History. Alfred A. Knopf, 1997)
  • "Dragonflies kill their prey in the air and eat it on the wing. They feed on aerial plankton, which consists of any sort of small living thing that happens to be aloft—mosquitoes, midges, moths, flies, ballooning spiders."
    (Richard Preston, "Flight of the Dragonflies." The New Yorker, December 3, 2012)
  • "I saw through the front blinds, which my mother always kept at a half-slant--'inviting but discreet'--that Grace Tarking, who lived down the street and went to a private school, was walking with ankle weights strapped to her feet."
    (Alice Sebold, The Lovely Bones. Little, Brown, 2002)
  • "A raw new development begins on the other side of my mother's meadow, which she has not been able to mow this fall, since her injuries prevent her from getting up on the tractor."​
    (John Updike, Self-Consciousness. Random House, 1989)

The Difference Between Restrictive Clauses and Nonrestrictive Clauses

"To make this as short and brutal an explanation as possible, think of a restrictive clause as a liver: a vital organ of the sentence that cannot be removed without killing it. A nonrestrictive clause, however, is more like the appendix or tonsils of a sentence: It may be desirable to have but can be removed without dying (so long as one does so carefully)." (Ammon Shea, Bad English: A History of Linguistic Aggravation. Perigee, 2014)

Nonrestrictive Relative Pronouns and Intonation Patterns

"Non-restrictive relative clauses are introduced by the marked relative pronouns who(m) for human referents and which for non-human referents and for situations. The marked pronoun in conjunction with a caesura [i.e., a pause] before and after the clause clearly sets off the non-restrictive relative clause from the main clause; in written discourse non-restrictive relative clauses are set off by commas. In this way the speaker indicates that the characterising event described in the non-restrictive clause is meant as a parenthetical aside. This intonation pattern differs strongly from the uninterrupted flow of restrictive relative clauses."
(Günter Radden and René Dirven, Cognitive English Grammar. John Benjamins, 2007)

Summary: Characteristics of Nonrestrictive Relative Clauses

"The following characteristics distinguish nonrestrictive relative clauses:

- In writing, they are set off by commas. . . .
- In speech, they are set off by pauses and falling intonation at the end of the clause. . . .
- They can modify proper nouns. . . .
- They cannot modify any, every, no + noun, or indefinite pronouns such as anyone, everyone, no one, etc. . . .
- They cannot be introduced by that. . . .
- They cannot be stacked. . . .
- They can modify an entire sentence. . . .

The relative pronouns used in nonrestrictive relatives are the same as those used in restrictive relatives, except for that."
(Ron Cowan, The Teacher's Grammar of English: A Course Book and Reference Guide. Cambridge University Press, 2008)