Descartes

Innate Idea  -  An innate idea is an idea that is present in the mind at birth. Descartes believed that inborn in our minds are certain mathematical ideas (such as the ideas of geometrical shapes), metaphysical ideas (such as the idea of God and of essences), and eternal truths (such as the truth that something cannot come from nothing). These innate ideas play a central role in his theory of knowledge.

Substance - According to the Scholastics, a substance is the most basic unit of existence. Descartes agreed, but he reduced the types of substances in the world from an innumerable mass to only three—body, mind, and God (a variation on the substance of mind).

Corporeal substance

Nemo extensio in longum, latum et profundum, substantiae corporea naturam constituit (extension in length, breadth, and thickness constitutes the nature of corporeal substance). (Principles of Philosophy, Book I).

I observed that nothing at all belonged to the nature of essence of body except that it was a thing with length and breadth and depth, admitting of various shapes and various motions. I found also that its shapes and motions were only modes, which no power could make to exist apart from it; and on the other hand that colours, odours, savours and the rest of such things, were merely sensations existing in my thought and differing no less from bodies than pain differs from the shape and motion of the instrument which inflicts it.

Mode  -  According to Descartes a mode, is a determinate way of being a principal attribute. All modes of body are determinate ways of being extended. Examples of modes of body would include squareness, being two inches by two inches by two inches, being unified. All modes of mind are determinate ways of being thought, e.g. imagining a unicorn, believing I will have steak for dinner tonight, wishing you would go away.

Secondary Qualities  -  Secondary qualities include the qualities of color, odor, smell, taste, heat, cold, pain, pleasure. According to Descartes, there is nothing in the world corresponding to our ideas of these qualities. What we see as "red", for instance, is really just a colorless arrangement of corpuscles, which, by their particular size, shape, and motion, have the power to produce in us the sensation of redness.