1. Not capable of being lost or impaired by neglect, by disuse, or by the claims of another founded on prescription. The right of navigation, fishing, and others that may be exercised on the sea, belonging to the right of mere ability, are imprescriptible. (Vattel (Trans))
2. Not derived from, or dependent on, external authority; self-evidencing; obvious. The imprescriptible laws of the pure reason. (Colerridge)
Origin: Pref. Im- not – prescriptible: cf. F. Imprescriptible.