fleeting

(verb) move along rapidly and lightly; skim or dart. Synonyms: flit, flutter, fleet, dart. Examples: "The hummingbird flitted among the branches."

(verb) disappear gradually. Synonyms: evanesce, fade, blow over, pass off, fleet, pass. Examples: "The pain eventually passed off."

(adj) lasting for a markedly brief time. Synonyms: fugitive, momentaneous, momentary. Examples: "A fleeting glance." "Fugitive hours." "Rapid momentaneous association of things that meet and pass." "A momentary glimpse."