Clause: matrix clause

A clause that contains another clause within it as a constituent. It is defined by the relationship of containment rather than just being “the main part” of a sentence.

Relationship of containment

A matrix clause is the “wrapper.” If Clause B is a constituent of Clause A, then Clause A is the matrix clause for Clause B.

I think [that you are right].

Matrix Clause: I think that you are right.
Subordinate Clause: that you are right.

Matrix vs. main clause

While often used interchangeably in traditional grammar, there is a technical distinction:

• Main Clause: A clause that is not subordinate to any other clause. It can stand alone as a complete sentence.

• Matrix Clause: A relative term. A clause can be both a subordinate clause (to something above it) and a matrix clause (to something inside it).

  Hierarchy Example:

[I believe [that she said [that he left]]].

The entire sentence is the Main Clause.

“I believe that she said that he left” is the Matrix for the “that she said…” clause.

“that she said that he left is a subordinate clause, but it is also the Matrix for the “that he left” clause.

Structural roles within the matrix

The subordinate clause typically fills a specific functional slot within its matrix:

She knows [that it’s late]. (complement, the subordinate clause is the object/complement of knows).

I’ll call you [if I’m late]. (the subordinate clause is a conditional adjunct within the matrix).

[That he lied] is obvious. (the subordinate clause is the subject of the matrix).

Matrix clauses and parentheticals

It is important to distinguish a matrix clause from a supplement or parenthetical.

I suspect [he is lying] (matrix, syntactically integrated).

He is lying, [I suspect] (non-matrix, supplemental)

In the second example, I suspect is a clinical supplement. It does not “contain” the other clause; rather, it is attached to it. Therefore, I suspect is not the matrix clause here.