fleetingly
🇺🇸
/ˈfliːtɪŋli/
🇬🇧
/ˈfliːtɪŋli/
lasting for a very short time
She smiled fleetingly, her happiness gone as quickly as it had come.
彼女は一瞬に微笑んで、その幸せは来たように速く消えていった。