Define modulus of elasticity stress, stain and poisson’s ratio?

Modulus of Elasticity(K) : With in elastic limit the ratio of stress to strain is called modulus
of Elasticity (K)

$\therefore \mathrm{K}=\frac{\text{ stress }}{\text{ strain }}$S.I. Units : Nm^-2 (or) Pascal

Stress : The ratio of restoring force to cross sectional area Stress $=\frac{\mathrm{F}}{\mathrm{A}}$

SI units Nm^–2 (or) Pascal

Strain : The ratio of change in dimension to original dimension is called strain.

No units and No dimension.
Poisson's ratio : The ratio of lateral contraction strain to longitudinal elongational strain.
No units and No dimension.