What is the meaning of fleeting?

verb

• Move along rapidly and lightly; skim or dart.
  • usage: "The hummingbird flitted among the branches"
  • synonyms: flit, flutter, fleet, dart
• Disappear gradually.
  • usage: "The pain eventually passed off"
  • synonyms: evanesce, fade, blow over, pass off, fleet, pass

adjective

• Lasting for a markedly brief time.
  • usage: "a fleeting glance"; "fugitive hours"; "rapid momentaneous association of things that meet and pass"; "a momentary glimpse"
  • synonyms: fugitive, momentaneous, momentary