fugacious

Fugacious is often used to describe immaterial things like emotions, but not always. Botanists, for example, use it to describe plant parts that wither or fall off before the usual time. Things that are fugacious are fleeting, and etymologically they can also be said to be fleeing. Fugacious derives from the Latin verb fugere, which means "to flee." Other descendants of fugere include fugitive, refuge, and subterfuge.