Source : Webster's Revised Unabridged Dictionary (1913)

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.

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

Source : WordNet®

celerity
     n : a rate that is rapid [syn: {quickness}, {rapidity}]