second (unit of time); arc second (angular measurement unit); (coll.) instantly

stopwatch

(time) second

millisecond, ms

second hand (of a clock)

microsecond, µs, 10^-6 s

nanosecond, ns, 10^-9 s (PRC); Taiwan equivalent: 奈秒

to count down the remaining seconds (e.g. in games, rocket launches, New Year's Eve); (of a boxing referee) to administer the count following a knock-down, starting from "one"