contend

Contend comes through Middle English contenden and Old French contendre from Latin contendere, "to stretch out, strive after, contend," built from com- ("together") plus tendere ("to stretch").

The facts don't detail a specific shift in meaning over time, but the Latin sense of striving or stretching toward something carries straight through into the English word's meaning of arguing or competing.

It shares its tendere root with attend, extend, intend, and subtend — all words built on the idea of stretching, just in different directions.