Meaning

noun a substance capable of bringing about the reduction of another substance as it itself is oxidized; used in photography to lessen the density of a negative or print by oxidizing some of the loose silve

originEtymology tree English reduce Proto-Indo-European *-onts Latin -ns Latin -āns Old French -antbor. Proto-Indo-European *-onts Proto-Germanic *-ndz Proto-West Germanic *-andī Old English -ende Middle English -ant English -ant English reductant From reduce + -ant.

Etymology from Wiktionary, CC BY-SA 3.0