D defs.my
Entry 2 senses Webster, 1913

irradiance

/(ĭr*rā"dĭ*ans)/ · ir·ra·di·ance · IPA /ɪˈɹeɪ.di.əns/
01 n. The act of irradiating; emission of rays of light.
  1. 1.
    The act of irradiating; emission of rays of light.
  2. 2.
    That which irradiates or is irradiated; luster; splendor; irradiation; brilliancy.