Etymology tree Proto-Indo-European *ten- Proto-Indo-European *tend-der. Proto-Italic *tendō Latin tendō Proto-Indo-European *-tis Proto-Indo-European *-Hō Proto-Indo-European *-tiHō Proto-Italic *-tiō Latin -tiō Latin tēnsiōder. Middle French tensionbor. English tension Borrowed from Middle French tension, from Latin tēnsiō.