Used as a verb it means to bleach the hair and remove current color.
When used as a noun it refers to the chemical composition designed to remove color from the hair. Bleach is sometimes referred to as a pre-lightening or decolorizing treatment.
Daily Hair Tip
A humectant hair product attracts moisture to the hair while an anti-humectant repels moisture. Use a humectant to combat static electricity and an anti-humectant to deal with humidity.