verb (used with object), ir·ra·di·at·ed, ir·ra·di·at·ing.
verb (used without object), ir·ra·di·at·ed, ir·ra·di·at·ing.
- to emit rays; shine.
- to become radiant.
- irrational number,
Origin of irradiate
c.1600, "to cast beams of light upon," from Latin irradiatus, past participle of irradiare "shine forth," from assimilated form of in- "into, in" (see in- (2)) + radiare "to shine" (see radiate). Meaning "expose to radiation other than light" (originally X-rays) is from 1901. Related: Irradiated; irradiating.