inconstant
/(ˌ)in-ˈkän(t)-stənt/
adjective
likely to change frequently without apparent or cogent reason
inconstant fickle capricious mercurial unstable mean lacking firmness or steadiness (as in purpose or devotion). inconstant implies an incapacity for steadiness and an inherent tendency to change. fickle suggests unreliability because of perverse changeability and incapacity for steadfastness.