/ˈsʌbdʒɪkt/ (noun/adjective), /səbˈdʒɛkt/ (verb)
[noun] A person, thing, or topic that is being discussed, studied, or dealt with. It can also mean a person who is under the authority of a ruler or government, or a course of study in school.
Every grammar 'subject' and every school 'subject' share the same dark Latin root meaning 'thrown under' — as if pinned beneath a ruler's boot.
The word 'subject' reaches back to the Latin verb subicere, meaning 'to throw under' or 'to place beneath', itself built from two parts: sub, meaning 'under', and iacere, meaning 'to throw'. This same iacere root gave English a surprisingly large family of words — Latin iacere → Old French jeter → English 'jet' (as in a jet of water), and Latin proicere → Old French projecter → English 'project', and Latin obiectum → Old French object → English 'object'. In every case, the core idea of something being thrown or placed in a particular direction is lurking just beneath the surface.
The past participle of subicere was subiectus, meaning literally 'thrown under' or 'placed below'. In the social world of ancient Rome, this carried a powerful political meaning — a subiectus was a person placed under the authority of another, a subordinate. Latin subiectus → Old French suget or sogit → Middle English suget or subject, arriving in English in the late 14th century. The earliest English uses kept this political flavour entirely: a 'subject' was someone who lived under the rule of a monarch or lord, with all the powerlessness that implied.
The philosophical and grammatical uses of the word developed in parallel, flowing through medieval Latin scholarship. Latin philosophers used subiectum to translate the Greek word hypokeimenon — literally 'that which lies under' — the term Aristotle used to describe the underlying substance or topic of a discussion. This gave rise to 'subject' meaning the thing being talked about or examined, a sense that passed through medieval Latin subiectum → Old French subiect → Middle English subject by the 14th and 15th centuries. Remarkably, the same word that described a powerless person under a king also came to describe the central focus of intellectual attention.
Grammar borrowed the word in the 16th century to name the part of a sentence that performs the action of the verb — the grammatical 'subject' as opposed to the 'object'. This use is a direct loan from Latin grammar, where grammarians used subiectum (the thing placed under discussion) to describe what the sentence was fundamentally about. Latin subiectum → Renaissance English grammatical writing → everyday Modern English grammar. It is a beautifully circular logic: the subject of a sentence holds power over the verb, even though the word originally meant someone with no power at all.
Over the centuries, 'subject' quietly accumulated meanings that seem almost unrelated until you trace them back to that original image of being placed under something. A school subject is something placed under your attention. To be subject to a law means to be placed under its authority. To subject someone to an experience means to push them beneath it. Even in science, the 'subject' of an experiment — the person being tested — carries a faint echo of that original Latin subordination: someone placed beneath the researcher's control. Few words in English carry so many different lives inside a single spelling.