Webster’s Revised Unabridged Dictionary · 1913
Celerity
Ce·ler′i·ty (sē·lĕr′ĭ·ty̆), n. [L. celeritas, from celer swiftm speedy: sf. F. célérité.] Rapidity of motion; quickness; swiftness.
Time, with all its celerity, moves slowly to him whose whole employment is to watch its flight. Johnson.