expansivity

(noun) the fractional change in length or area or volume per unit change in temperature at a given constant pressure. Synonyms: coefficient of expansion.

(noun) a quality characterized by magnificence of scale or the tendency to expand. Synonyms: expansiveness. Example: "The expansiveness of their extravagant life style was soon curtailed."

(noun) a friendly open trait of a talkative person. Synonyms: effusiveness, expansiveness.