| Fugacity 1. (n.) The quality of being fugacious; fugaclousness; volatility; as, fugacity of spirits. 2. (a.) Uncertainty; instability. Thesaurus Entries caducity, changeableness, corruptibility, death, ephemerality, ephemeralness, evanescence, finitude, fleetingness, impermanence, impermanency, instability, momentariness, mortality, mutability, perishability, transience, transiency, transientness, transitoriness, volatility |