fleeting /ˈfliːtɪŋ/adjective 2noun 1forms 2 adjective2 •Passing quickly; of short duration.During the fleeting summer months of his field season, when the outer vestiges of winter melted briefly, there were ponds and pools and lakes of water everywhere. — 2003 •That which flees, especially quickly; fugitive. noun1 •(US) 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. formsmore fleeting · most fleeting
