impermanent

1 intended to last, continue, or serve for a limited time built an impermanent structure to serve for the archaeologists' living quarters during the dig Synonyms ad interim, temporary, interim, provisional, provisionary, provisory, short-termRelated Words acting; alternate, proxy, substitute; expedient, improvised, makeshift; intermediary, intermediate, transitional; ephemeral, fleeting, fugitive, short-lived, transitory; conditional, contingent, limited, qualified, short-range, tentative; replaceable, terminable, terminateNear Antonyms final, fixed, set, settled; unconditional, unlimited, unqualified; extended, lasting, long-range, standing; dateless, deathless, endless, enduring, eternal, everlasting, immortal, perpetual, timeless, undying, unendingAntonyms long-term, permanent

2 lasting only for a short time a summer romance that was an impermanent fancy, quickly forgotten Synonyms brief, deciduous, ephemeral, evanescent, flash, fleeting, fugacious, fugitive, momentary, passing, short-lived, temporary, transient, transitoryRelated Words little, short, shortish; acting, interim, provisional, short-termNear Antonyms lifelong; continuing, durable, persistent; imperishable, indefectible, indestructibleAntonyms ceaseless, dateless, deathless, endless, enduring, eternal, everlasting, immortal, lasting, long-lived, permanent, perpetual, timeless, undying, unending