In terms of sentence construction it is called the 'subject'.
Give the letter to Mary. to whom?The letter is for Mary. for whom?
What is used for things. Whom is used for a person.
A literary term for a small stream is "brook."
A noun that answers the question "To Whom?" ot "To What?" or "For Whom?" or "For What?"
"Answers what" refers to providing information or clarification about a topic or question, while "answers whom" refers to identifying the person or entity that is the subject of a question.
Proper nouns
A literary term is what you can use to define the makeup of a story. Sample literary terms include characterization, plot, genre, foreshadowing, and more.
The part of speech that answers "what" or "whom" in a sentence is a pronoun. Pronouns are words like "he," "she," "it," "they," "who," and "what" that replace nouns in a sentence.
an indirect object
The subject of a sentence answers the question "what" or "whom." It refers to the person or thing that is performing the action or being described in the sentence.
The protagonist is the main character in a story who drives the plot forward and often undergoes personal growth or transformation. They are typically the character with whom the audience is meant to empathize or root for.
Whom = ος / η / ο . Hope that answers your question.