How do you spell Illustration

Available Definitions:
1)  n. - The act of illustrating; the act of making clear and distinct; education; also, the state of being illustrated, or of being made clear and distinct.
2)  n. - That which illustrates; a comparison or example intended to make clear or apprehensible, or to remove obscurity.
3)  n. - A picture designed to decorate a volume or elucidate a literary work.