fleeting

1. 1
   adjective

   Passing quickly and lasting only a short time before it ends.

   Like a shooting star: bright for a second, then gone.

   A fleeting glance passed between the two old friends across the crowded room.

   Fame can be fleeting, gone almost as soon as it arrives.

   Similarbrief, passing, momentary, short-lived, temporary

   Oppositelasting, permanent, enduring, long-lived

   Note

   An adjective built from a verb of motion: fleet + -ing, going back through Middle English fleten to Old English flēotan, 'to float'. What is fleeting drifts past rather than simply stopping. It attaches readily to sightings and to stretches of time: a fleeting glimpse of a train crew, fleeting summer months, fleeting youth. Transient, ephemeral and fugacious cover much the same ground.

2. 2
   verb

   Present participle of fleet.

   Note

   The verb form shares its spelling with the 'brief' adjective, which grew out of it. It can take an object or stand alone: to fleet the hours is to let them pass lightly, in mirth and joy, while joy fleeting away needs no object. Sailors had their own use, fleeting a tackle by drawing its blocks apart. The oldest meaning, 'to float', is now obsolete.

3. 3
   nounUSuncountable

   An automatic mode on an absolute signal that holds a route open for several following trains, so the dispatcher need not reset it for each one.

   Like a turnstile left unlocked so a line of people can pass through one after another without inserting a coin each time.

   Operators rely on fleeting to move closely spaced trains through busy junctions efficiently.

   Once fleeting was set, each following train received a clear signal automatically.

   Note

   American railway signaling uses the word as a mass noun, with no article: fleeting is set, or a route runs on fleeting. Once it is on, the signal returns to a proceed aspect by itself after each train clears, so a string of trains moving in the same direction goes through on a single setting. It names an operating mode, not a quality, so it never takes the comparatives of the adjective.

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