expansivityrare.|ɛkspænˈsɪvɪtɪ| [f. as prec. + -ity.] = expansiveness. 1837Carlyle MirabeauMisc.Ess. (1888) V. 231 Offences (of elasticity or expansivity) have accumulated.1838Blackw. Mag. XLIV. 612 The expansivity and soaring heavenwardness of the gases have full play.