An Etymological Dictionary of Astronomy and Astrophysics

Change of volume and/or shape of a body, or part of a body, due to an applied → stress. When a body is deformed
by such a force, through compression or distension, the strain is the ratio of the dimensional change to the original or un-strained dimension. The strain may be a ratio of lengths, areas, or volumes. See also → shear.

Etymology (EN): M.E. streinen (v.), from O.Fr. estreindre “to bind tightly, clasp, squeeze,” from L. stringere “to bind or draw tight,” from PIE base *strenk- “tight, narrow; pull tight, twist;” cf. Gk. strangein “twist;” Lith. stregti “congeal;” O.H.G. strician “mends nets;” Ger. stramm, Du. stram “stiff.”

Etymology (PE): Šepil “squeeze; fondness” (Dehxodâ) of unknown origin.