(Expanding on
Webster 1913,
Tem"per, n. def. 5.) A
quality that someone possesses: a certain
flammability of
attitude. The
tendency to
fly off the handle easily, to become (possibly
violently)
irritated or
enraged with little or no apparent
cause.
When a child becomes piqued, mother may mutter (condescendingly) temper, temper.... Apocryphally, redheads supposedly "have a temper". Probably from (or just related to) temperament: a bad one.