Inanity \In*an"i*ty\, n.; pl. {Inanities}. [L. inanitas, fr. inanis empty: cf. F. inanit['e]. See {Inane}.] 1. Inanition; void space; vacuity; emptiness. 2. Want of seriousness; aimlessness; frivolity. 3. An inane, useless thing or pursuit; a vanity; a silly object; -- chiefly in pl.; as, the inanities of the world.