illuminate v.

late 14c., "spiritual enlightenment," from Late Latin illuminationem (nominative illuminatio), noun of action from past participle stem of Latin illuminare "to throw into light, make bright, light up;" figuratively, in rhetoric, "to set off, illustrate," from assimilated form of in- "in, into" (from PIE root *en "in") + lumen (genitive luminis) "light," from suffixed form of PIE root *leuk- "light, brightness." Meaning "action of lighting" in English is from 1560s; sense of "intellectual enlightenment" is from 1630s.

late 14c., "to enlighten spiritually;" mid-15c., "to light up, shine light on," from Old French illuminer (13c.), from Latin illuminare "make bright, light up" (see illumination). Related: illumined.

"to light up, illuminate," 1620s (obsolete), from *luminatus, past participle of Late Latin luminare "to shine," from Latin lumen (genitive luminis) "light," from suffixed form of PIE root *leuk- "light, brightness." Illuminate now does the job. An older verb was lumine (late 14c.); a newer one is luminize (1958). Related: Luminated; luminating; lumination; luminator.