"Simple subject" is the term used for the single word that is the subject of a verb. A simple subject will often have modifiers before or after it, but, once these are removed, the word left is the simple subject.

A simple subject is a noun word or group of noun words that tell you what a sentence is about. It is the who or what that is performing the action in a sentence (as communicated by a verb). The simple subject also is not modified: It is the sentence subject standing alone.

A simple subject is the main noun or pronoun in a sentence, serving as the focus of the action. It determines the singular or plural form of the verb used in the sentence. Simple subjects can be identified by omitting modifiers like adjectives, articles, and prepositional phrases, narrowing down to the fundamental noun or pronoun.

A simple subject is a main word or words that tell whom or what a sentence discusses. The simple subject is only who or what is “doing” the verb, without any modifiers.

In traditional grammar, a simple subject is the particular noun or pronoun that tells who or what a sentence or clause is about.