Well, I finally found a definition that was easy to understand. According to WiseGeek.com:
A subject noun is the subject of a sentence and usually, but not always, comes before the main verb in a sentence. The subject performs the action described by the verb and can be identified in a sentence by the answer to the question “who did it?” or “what did it?” A noun is a name word used for a person, thing, animal, or something abstract and these nouns can function in a sentence as a subject, a subject or object complement, direct or indirect object, an adjective, adverb or appositive.
- Grammatical Wednesday’s – Eight Parts of Speech (blackwomenhaveitgoingon.wordpress.com)
- Parts of speech! (mrskimoto.org)
- Grammatical Wednesday’s – Subject vs. Noun (blackwomenhaveitgoingon.wordpress.com)