fleeting

adjective

  1. 1

    Passing quickly; of short duration.

  2. 2

    That which flees, especially quickly; fugitive.

noun

  1. 1

    An automatic operation mode of an absolute signal that reserves a route for several trains following one another, without the need for dispatcher to re-set the route for each train.

verb

  1. 1

    present participle and gerund of fleet

Also useful for “fleeting”:Unscrambler