second - definition of second by The Free Dictionary
sec·ond 1 (sĕk′ənd) n. 1. a. A unit of time equal to one sixtieth of a minute. b. The time needed for a cesium-133 atom to perform 9,192,631,770 complete oscillations. ... second 1 [ɐadj, adv, n, vt a ˈsɛk/ənd; ɐvt b sɪˈkɒnd]...