c. 1300, clarte, clerte "brightness, radiance; glory, splendor," from Old French clerte, clartet (Modern French clarté) "clarity, brightness," from Latin claritas "brightness, splendor," also, of sounds, "clearness;" figuratively "celebrity, renown, fame," from clarare "make clear," from clarus "clear" (see clear (adj.)).
Modern form is first attested early 15c., perhaps a reborrowing directly from Latin. Original senses are obsolete; meaning "clearness" (of color, judgment, style, etc.) is from mid-15c.
"one who or that which makes dim," 1822, agent noun from dim (v.). Of mechanisms for reducing the brightness of electric lights, from 1905.