Cognition, n.
Etymology: [L. cognitio, fr. cognoscere, cognitum, to become acquainted with, to know; co- + noscere, gnoscere, to get a knowledge of. See Know, v. t.]
1. The act of knowing; knowledge; perception. I will not be myself nor have cognation Of what I feel: I am all patience. Shak.
2. That which is known.
Shades of meaning
Fernald has no entry of its own for cognition; he lists it under knowledge.
Where he writes about it:
Simple perception gives a limited knowledge of external objects, merely as such; the cognition of the same objects is a knowledge of them in some relation; cognizance is the formal or official recognition of something as an object of knowledge; we take cognizance of it. — from knowledge