(n.) The quality or state of being swift; speed; quickness; celerity; velocity; rapidity; as, the swiftness of a bird; the swiftness of a stream; swiftness of descent in a falling body; swiftness of thought, etc.

abruptness agility air speed alacrity bat brevity briefness briskness celerity decisiveness dispatch expedition expeditiousness fastness feverishness flight flit flurry furiousness gait ground speed haste hastiness hurriedness hurry hustle immediacy immediateness impetuosity impetuousness impulsiveness instantaneousness knots lightning speed miles per hour nimbleness pace precipitance precipitancy precipitation precipitousness promptitude promptness punctuality punctualness quickness rapidity rashness readiness round pace rpm rush rustle sharpness shortness smartness snappiness speed speediness spryness suddenness summariness swift rate velocity