1. (a friendly open trait of a talkative person)
wylewność
synonim: effusiveness
synonim: expansiveness

2. (the fractional change in length or area or volume per unit change in temperature at a given constant pressure)
współczynnik rozszerzalności cieplnej: : synonim: coefficient of expansion

3. (a quality characterized by magnificence of scale or the tendency to expand
"the expansiveness of their extravagant life style was soon curtailed")
ekspansywność: : synonim: expansiveness