Imperishable, a.
Etymology: [Pref. im- not + perishable: cf. F. impérissable.]
Not perisha ble; not subject to decay; indestructible; enduringpermanently; as, an imperishable monument; imperishable renown. -- Im*per"ish*a*ble*ness, n. -- Im*per"ish*a*bly, adv.
Shades of meaning
Fernald has no entry of its own for imperishable; he lists it under eternal.
He lists it without comment; the entries above explain its neighbors.