The Collaborative International Dictionary of English v.0.48:
Elasticity \E`las*tic"i*ty\ ([=e]`l[a^]s*t[i^]s"[i^]*t[y^]), n.
[Cf. F. ['e]lasticit['e].]
1. The quality of being elastic; the inherent property in
bodies by which they recover their former figure or
dimensions, after the removal of external pressure or
altering force; springiness; resilience; tendency to
rebound; as, the elasticity of caoutchouc; the elasticity
of the air.
2. Power of resistance to, or recovery from, depression or
overwork; -- usually referred to as resilience.
Coefficient of elasticity, the quotient of a stress (of a
given kind), by the strain (of a given kind) which it
produces; -- called also coefficient of resistance.
Surface of elasticity (Geom.), the pedal surface of an
ellipsoid (see Pedal); a surface used in explaining the
phenomena of double refraction and their relation to the
elastic force of the luminous ether in crystalline media.