swift·ness \-f(t)nə̇s\noun (-es) Etymology: Middle English swiftnes, from Old English, from swift (I) + -nes -ness 1.: the quality or state of being swift : speed, celerity < the swiftness of a lizard catching a fly — Vicki Baum > 2.: the fact of being swift < when swiftness of action was indispensable to surprise >