Anything conceived or imagined in the mind, an idea, a mental representation; a mental image, idea, or concept of anything. Now chiefly Philosophy.

Originally in Philosophy: a general idea or notion, a universal; a mental representation of the essential or typical properties of something…

Philosophy. An idea or mental image which corresponds to some distinct entity or class of entities; = concept, n. 2. Obsolete.

The action or process of presenting to the mind or imagination; an instance of this; (also) the result of this process; an image or picture…

An idea in a person's mind; a person's conception or understanding of something.

That which is capable of being said; a notion or idea expressible in words.

A false or spurious concept; (Philosophy) a notion which is sometimes treated as a concept though it cannot be properly conceptualized or grasped…

That which is thought; the actual processes of thought, as opposed to the ideal thought-processes.