Entry 1 sense Webster, 1913 Celerity /səl-ĕr'-ət-ē/ · Ce·ler·i·ty · IPA /səˈlɛr.ɪ.ti/ 01 n. Rapidity of motion; quickness; swiftness. 1. Rapidity of motion; quickness; swiftness. “Time, with all its celerity, moves slowly to him whose whole employment is to watch its flight.” — Johnson.