1 light (up), brighten, lighten, throw or cast or shed light on or upon:
She had only a single candle to illuminate her sewing.
2 clarify, throw or cast or shed light on or upon, enlighten, clear up, elucidate, explain, explicate, reveal:
The lectures on Heidegger illuminated his philosophy to some extent.
3 rubricate, decorate, adorn, embellish, ornament:
The museum has the best collection of illuminated manuscripts.