"reduce in size or scale," 1945, American English, from down (adv.) + scale (v.). In business, especially, "to reduce the size of an operation." Related: Downscaled; downscaling. From 1966 as an adjective.
mass-produced downscale versions of high-priced fashions
down-market
downplay
downpour
downrange
downright
downscale
downside
downsize
downspout
downstairs
downstream