1. The act or state of knowing; clear perception of fact, truth, or duty; cognition. 2. That which is or may be known; the object of an act of knowing; a cognition; -- chiefly used in the plural. 3. That which is gained and preserved by knowing; instruction; acquaintance; enlightenment; learning; scholarship; erudition. 4. That familiarity which is gained by actual experience; practical skill; as, a knowledge of life. 5. Scope of information; cognizance; notice; as, it has not come to my knowledge.