Other forms: evanescently
A beautiful sunset, a rainbow, a wonderful dream right before your alarm clock goes off — all of these could be described as evanescent, which means “fleeting” or “temporary.”
Evanescent comes from the Latin ex, meaning "out of," and vanescere, meaning "to vanish." When pronouncing this word, emphasize the third syllable and note that the c is silent. You might want to practice saying evanescent a few times right now; if you stumble over pronunciation when you need this word the most, whatever you’re describing — be it a shooting star or a whiff of fragrant perfume — will be gone.