A complete subject combines with a complete predicate to make a complete sentence in English grammar. The complete subject has as its base a noun or pronoun that tells about to what or whom the sentence is referring. The complete predicate contains a verb as its base.
A complete subject can have as few as one word or it may contain several words. Other words that frequently occur in complete subjects are conjunctions, adjectives and articles, a special kind of adjective. Prepositional phrases that modify simple subjects also sometimes appear. Prepositional phrases each contain prepositions, noun(s) or pronoun(s), and occasionally adjectives.
In the sentence, "Stop!" the complete subject is the word "you," which is implied. In the sentence, "He ate," the complete subject is "he." The sentence, "The girl in the blue dress with the white sweater sang" has "the girl in the blue dress with the white sweater" as its complete subject.
A complete subject, no matter how many words it has, does not make sense when it stands alone. It must have a predicate. Like the complete subject, the complete predicate may have one word or several. In each of the three sentences above, the complete predicate contains only one word: "stop," "ate" and "sang." In the sentence, "She baked a cake with seven layers covered in rich chocolate frosting," the complete predicate is "baked a cake with seven layers covered in rich chocolate frosting."