1. n. [Geophysics]

An elastic constant named after British physicist Thomas Young (1773 to 1829) that is the ratio of longitudinal stress to longitudinal strain and is symbolized by E. It can be expressed mathematically as follows:

E = (F/A) / (ΔL/L),

where
E = Young's modulus
F = longitudinal force
A = area
F/A = longitudinal stress
ΔL = change in length
L = original length
ΔL/L = longitudinal strain.

See: elastic constants