early 14c., "person under control or dominion of another,"
from O.Fr. suget, subget "a subject person or thing" (12c.),
from L. subiectus, noun use of pp. of subicere "to place under," from sub "under" + combining form of iacere "to throw" (see jet (v.)).
In 14c., sugges, sogetis, subgit, sugette; form re-Latinized in English 16c.
Meaning "person or thing that may be acted upon" is recorded from 1590s.
Meaning "subject matter of an art or science" is attested from 1540s, probably short for subject matter (late 14c.), which is from M.L. subjecta materia, a loan translation of Gk. hypokeimene hyle (Aristotle), lit. "that which lies beneath."
Likewise some specific uses in logic and philosophy are borrowed directly from L. subjectum "foundation or subject of a proposition," a loan-translation of Aristotle's to hypokeimenon. Grammatical sense is recorded from 1630s. The adj. is attested from early 14c.
(Greek: ὑποκείμενον), later often material substratum, is a term in metaphysics which literally means the "underlying thing" (Latin subiectum).
To search for the hypokeimenon is to search for that substance which persists in a thing going through change— its essential being.
According to Aristotle's definition (in Categories), hypokeimenon is something which can be predicated by other things, but cannot be a predicate of others.
The existence of a material substratum was posited by John Locke, with conceptual similarities to Baruch Spinoza's substance and Immanuel Kant's concept of the noumenon (in The Critique of Pure Reason).