the.com/subject

means The person or thing a statement, law, or ruler has power over — or, grammatically, the noun doing the action in a sentence.

from From Latin subjectus, 'thrown or placed under,' built from sub- ('under') plus jacere ('to throw'). A subject was literally someone cast beneath the authority of a king — the same root that gives us 'project' (thrown forward) and 'reject' (thrown back). The grammatical sense followed centuries later, when scholars borrowed the word for whatever idea a sentence is 'placed under' discussion.