From Old English 'drēosan' (to fall), with the frequentative -le suffix making it 'little repeated falling.'
Light rain falling in very fine drops.
Probably a frequentative of Middle English 'dresen' (to fall), from Old English 'drēosan' (to fall, drip). The -le suffix indicates repeated small action—drizzle is etymologically 'little repeated falling.' Key roots: *dreus- (Proto-Germanic: "to fall, to drip").