An adjective clause (also called a relative clause) is a type of dependent clause that acts as an adjective. This means it contains a subject and a verb, but it functions entirely to describe a noun.
Adjective clauses always come directly after the noun they modify and usually begin with a relative pronoun: who, whom, whose, which, or that.
Examples of Adjective Clauses
- The book that I bought yesterday is already missing. (The clause describes "The book".)
- The man who lives next door is a doctor. (The clause describes "The man".)
- The company, which was founded in 1990, just went bankrupt. (The clause describes "The company".)
Essential vs. Non-Essential Clauses
- Essential (Restrictive) Clauses: These provide necessary information to identify the noun. Do not use commas. We generally use that or who.
- The students who study hard will pass the test. (We are only talking about the specific students who study hard).
- Non-Essential (Non-Restrictive) Clauses: These provide extra, bonus information. The sentence still makes perfect sense without them. You must use commas to separate them from the rest of the sentence. We use which (for things) or who (for people).
- My grandfather, who is 90 years old, still runs every morning.