INVARIABLE Dictionary entry overview: What does invariable mean? • INVARIABLE (noun) The noun INVARIABLE has 1 sense: 1. a quantity that does not vary Familiarity information: INVARIABLE used as a noun is very rare. • INVARIABLE (adjective) The adjective INVARIABLE has 1 sense: 1. not liable to or capable of change Familiarity information: INVARIABLE used as an adjective is very rare.