All of the following are considered parts of speech except

adjective.

clause.

conjunction.

preposition.

All are considered parts of speech except clause.

Clause

Explanation:

Parts of speech refer to the different classes of words that exist according to their syntactic functions. In English, the main parts of speech are noun, pronoun, adjective, determiner, verb, adverb, preposition, conjunction, and interjection.

A clause, then, is not a part of speech; it is, instead, a construction containing at least a subject and a verb, and that can express a complete thought (independent) or not (dependent).