undurable (?.)

• brittle
• capricious
• changeable
• corruptible
• deciduous
• dying
• ephemeral
• evanescent
• fading
• fickle
• fleeting
• flitting
• fly-by-night
• flying
• fragile
• frail
• fugacious
• fugitive
• impermanent
• impetuous
• impulsive
• inconstant
• insubstantial
• momentary
• mortal
• mutable
• nondurable
• nonpermanent
• passing
• perishable
• short-lived
• temporal
• temporary
• transient
• transitive
• transitory
• unenduring
• unstable
• volatile