evanescent
adjective
UK/ˌiː.vəˈnes.ᵊnt/
US/ˌev.əˈnes.ᵊnt/
Definitions of evanescent adjective
Lasting for a very short time before disappearing or being forgotten.
The rainbow was an evanescent beauty in the sky.
Their happiness was evanescent, quickly fading away.
The morning mist was an evanescent sight, disappearing as the sun rose.