that which forms a basic matter of thought, discussion, investigation, etc.

a subject of conversation.

a branch of knowledge as a course of study

He studied four subjects in his first year at college.

a motive, cause, or ground

a subject for complaint.

the theme of a sermon, book, story, etc.

the principal melodic motif or phrase in a musical composition, esp. in a fugue.

an object, scene, incident, etc., chosen by an artist for representation, or as represented in art.

a person who is under the dominion or rule of a sovereign.

a person who owes allegiance to a government and lives under its protection

four subjects of Sweden.

Grammar . (in English and many other languages) a syntactic unit that functions as one of the two main constituents of a simple sentence, the other being the predicate, and that consists of a noun, noun phrase, or noun substitute which often refers to the one performing the action or being in the state expressed by the predicate, as He in He gave notice.

a person or thing that undergoes or may undergo some action

As a dissenter, he found himself the subject of the group's animosity.

a person or thing under the control or influence of another.

a person as an object of medical, surgical, or psychological treatment or experiment.

a cadaver used for dissection.

Logic . that term of a proposition concerning which the predicate is affirmed or denied.

Philosophy .

that which thinks, feels, perceives, intends, etc., as contrasted with the objects of thought, feeling, etc.

the self or ego.

Metaphysics . that in which qualities or attributes inhere; substance.

being under domination, control, or influence (often fol. by to ).

being under dominion, rule, or authority, as of a sovereign, state, or some governing power; owing allegiance or obedience (often fol. by to ).

open or exposed (usually fol. by to )

subject to ridicule.

being dependent or conditional upon something (usually fol. by to )

His consent is subject to your approval.

being under the necessity of undergoing something (usually fol. by to )

All beings are subject to death.

liable; prone (usually fol. by to )

subject to headaches.

to bring under domination, control, or influence (usually fol. by to ).

to bring under dominion, rule, or authority, as of a conqueror or a governing power (usually fol. by to ).

to cause to undergo the action of something specified; expose (usually fol. by to )

to subject metal to intense heat.

to make liable or vulnerable; lay open; expose (usually fol. by to )

to subject oneself to ridicule.

Obsolete . to place beneath something; make subjacent.