Synonyms to fly-by-night

fugacious, brittle, capricious, changeable, corruptible, deciduous, dying, ephemeral, evanescent, fading, fickle, fleeting, flitting, flying, fragile, frail, fugitive, impermanent, impetuous, impulsive, inconstant, insubstantial, momentary, mortal, mutable, nondurable, nonpermanent, passing, perishable, short-lived, temporal, temporary, transient, transitive, transitory, undurable, unenduring, unstable, volatile, DP, Judas, absconder, at large, betrayer, bolter, brief, circumforaneous, convict, criminal, crook, deceiver, deserter, desperado, desperate criminal, disappearing, discursive, disengaged, displaced person, dissolving, divagatory, double-dealer, drifting, eloper, emigre, errant, escape artist, escaped, escapee, escaper, escapist, evacuee, evaporating, felon, fled, fleeing, fleer, floating, flown, footloose, footloose and fancy-free, free, gadding, gallows bird, gangster, gaolbird, gypsy-like, gypsyish, hot, imper