Strength

Chamber's Etymological of the English Language · 1895 · p. 582

strength, n. a stronghold. StTOOk, strook,4a.t and pa.p. of Strike. Strucken, struk'n, bad. and Pa.p. of Strike. Stub, stub, ru a stalk. Suage, Swage, swaj, v.t. or v.i. a form of A uage.