tension (n.)
1530s, "a stretched condition," from Middle French tension (16c.) or directly from Latin tensionem (nominative tensio) "a stretching" (in Medieval Latin "a struggle, contest"), noun of state from tensus, past participle of tendere "to stretch," from PIE root *ten- "stretch" (see tenet). The sense of "nervous strain" is first recorded 1763. The meaning "stress along lines of electromotive force" (as in high-tension wires) is recorded from 1785.