Add descriptive or identifying information to a noun
We saw leaves that were multi-colored. ‹ diagram ›
A relative clause
expresses descriptive or identifying information about a noun or noun phrase.
functions as adescriptor that limits or restricts the noun with the information that it adds. The leaves that were red and yellow fell to the ground. The leaves that were brown stayed on the tree.
takes form as a clause:
connected by a relative pronoun (that, which, who, whom or whose) . We saw the person who raked the leaves.
placed directly after the noun it modifies . The leaves that fell on the ground formed a multi-colored carpet.
adjusted to the temporal, locational and pronoun references in the main clause. He gave us a leaf that he had found earlier this morning.
Adjective Clause is a traditional grammar term for a clause that modifies a noun. However, in modern description "Adjective" is a term reserved for the word category Adjective (Adjective Properties). The clause is a modifier (not an adjective) to the noun. For this reason, the clause is referred to as a relative clause because it relates additional information to the noun.
Adverb Clause is a traditional grammar term for a clause that modifies the verb. However, the adverbs (when, while, because, since, though, if , so, etc.) have been reanalyzed and moved to the category Preposition (Preposition Properties). The structure is now called a Prepositional Phrase (not a clause). See Connective Prepositions.
Noun Clause is a traditional grammar term for an embedded clause that functions as the subject or "object" (predicate complement), of the clause in a similar way that a noun does. However, a clause is a structure; it cannot be a word, a "noun". (See Noun Properties). For this reason, the structure is called a subordinate clause or content clause because it adds information or content in a complex form within a clause.
See The Cambridge Grammar of the English Language, 11 §3.1 and Longman Grammar Of Spoken And Written English, 2.13.
