One bounded piece of work with a done state. A task is defined by being finishable.
Old North French tasque, from Vulgar Latin *tasca, an alteration of Latin taxa, from taxare (to assess, to tax); a task and a tax share a root because both were originally a duty assessed and imposed on someone.
One bounded piece of work with a done state. Defined by being finishable, the way the old assessed duty it descends from was always a fixed amount owed.