enlighten

Concise Oxford English Dictionary © 2008 Oxford University Press:
enlighten/ɪnˈlʌɪtn/

▶verb

• 1 give greater knowledge and understanding to.

  ■ give spiritual insight to.

• 2 (as adj. enlightened) rational, tolerant, and well informed.

– derivatives
enlightener noun.

– origin ME (in the sense ‘make luminous’): in early use from OE inlīhtan ‘to shine’; later from en-1, in-2 + lighten2 or the noun light1.