Noun. A substance you add to something to make it whiter. The two everyday meanings sit in different rooms of the house. In the laundry room: a whitener is a product put in the wash to make white clothes look bright white again, since cotton goes grey and yellow over time. Bleach is one kind; there are also 'optical brighteners' that do not remove stains but make the cloth reflect light so it looks whiter. On packaging you will also see the adjective form: whitening powder, whitening agent. In the kitchen: in British English a whitener is the powder or liquid you put in coffee or tea instead of milk — what many people call non-dairy creamer or coffee whitener. Offices and hotels keep little sachets of it. This use is fading a bit, but older speakers say it naturally. Beyond those, the word attaches freely to whatever is being whitened: a tooth whitener, a skin whitener, a shoe whitener for canvas sneakers. It is a plain, practical word — you meet it on labels and in shops far more than in conversation, where people just name the actual product ("pass me the bleach").

增白劑、漂白用品；（英式）咖啡奶精、奶精粉（non-dairy creamer）