Webster's 1828 Dictionary
SWIFTNESS
n.Speed; rapid motion; quickness; celerity; velocity; rapidity. Swiftness is a word of general import, applicable to every kind of motion, and to every thing that moves; as the swiftness of a bird; the swiftness of a stream; swiftness of descent in a falling body; swiftness of thought, etc.
Webster's 1913 Dictionary
SWIFTNESS
SWIFTNESS Swift "ness, n.
Defn: 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.
Oxford Thesaurus
swiftness
swiftness noun 1 the children had the swiftness of weasels: speed, speediness, quickness, velocity, celerity, fleetness, fastness, rapidity, rapidness, liveliness; informal nippiness. ANTONYMS slowness, sluggishness. 2 bankruptcy can happen with surprising swiftness: suddenness, abruptness, instantaneity, rapidity, rapidness, haste, hastiness, briskness, hurriedness, hurry. 3 the answer came with unwanted swiftness: promptness, immediateness, immediacy, instantaneousness, rapidity, rapidness, dispatch, punctuality; alacrity, expeditiousness, readiness, willingness. ANTONYMS lateness, tardiness.
Sanseido Wisdom Dictionary
swiftness
sw í ft ness 名詞 U すばやさ, 敏速さ .
The Wordsmith Dictionary