Undurable is an adjective that describes something that cannot last or endure for a long time. It is often used to describe something that is fragile, weak, or unstable. There are several synonyms for undurable, including perishable, fleeting, temporary, ephemeral, transitory, transient, momentary, evanescent, impermanent, and short-lived. These words can be used interchangeably with undurable to express a similar meaning. For example, "the undurable nature of the fragile vase" could be rewritten as "the perishable nature of the fragile vase" or "the fleeting nature of the fragile vase," depending on the context.