Noun | 1. | fixing agent - a chemical compound that sets or fixes something (as a dye or a photographic image) chemical compound, compound - (chemistry) a substance formed by chemical union of two or more elements or ingredients in definite proportion by weight fixative - a compound (such as ethanol or formaldehyde) that fixes tissues and cells for microscopic study hypo, sodium thiosulfate, sodium thiosulphate - a compound used as a fixing agent in photographic developing |