(Expanding on Webster 1913
, n. def. 5.) A quality
that someone possesses: a certain flammability
. The tendency
to fly off the handle
easily, to become (possibly violent
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.