消光

消光	xiāo guāng	(optics) extinction
消	xiāo	to diminish; to subside / to consume; to reduce / to idle away (the time) / (after 不 or 只 or 何 etc) to need; to require; to take
光	guāng	light; ray (CL:道) / bright; shiny / only; merely / used up; finished / to leave (a part of the body) uncovered