The Collaborative International Dictionary of English v.0.48:

Celerity \Ce*ler"i*ty\, n. [L. celeritas, from celer swiftm
   speedy: sf. F. c['e]l['e]rit['e].]
   Rapidity of motion; quickness; swiftness.
   [1913 Webster]

         Time, with all its celerity, moves slowly to him whose
         whole employment is to watch its flight. --Johnson.
   [1913 Webster]

WordNet (r) 3.0 (2006):

celerity
    n 1: a rate that is rapid [syn: celerity, quickness,
         rapidity, rapidness, speediness]

Moby Thesaurus II by Grady Ward, 1.0:

37 Moby Thesaurus words for "celerity":
   air speed, alacrity, bat, briskness, dispatch, expedition,
   expeditiousness, fastness, flight, flit, flurry, gait,
   ground speed, haste, hurry, hustle, instantaneousness, knots,
   legerity, lightning speed, miles per hour, pace, precipitation,
   promptitude, promptness, quickness, rapidity, round pace, rpm,
   rush, rustle, snappiness, speed, speediness, swift rate, swiftness,
   velocity