A relative clause
is a subordinate clause that modifies a noun phrase, most commonly a noun. For
example, the phrase "the man who wasn't there" contains the noun man,
which is modified by the relative clause who wasn't there. A relative clause
can also modify a pronoun, as in "he to whom I have written", or a
noun phrase which already contains a modifier, as in "the black panther in
the tree, which is about to pounce". The complete phrase (modified noun
phrase plus modifying relative clause) is also a noun phrase.
In many European languages, relative clauses are introduced
by a special class of pronouns called relative pronouns; in the previous
example, who is a relative pronoun. In other languages, relative clauses may be
marked in different ways: they may be introduced by a special class of
conjunctions called relativizers; the main verb of the relative clause may
appear in a special morphological variant; or a relative clause may be
indicated by word order alone. In some languages, more than one of these
mechanisms may be possible.
