Definition of temper:

part of speech: noun

A mixture of different qualities in due proportion; the state of a substance made up from the mixture of various ingredients; the state or constitution of the mind; disposition of mind; mood; irritation; the state of a metal as to its quality of hardness.

part of speech: verb

To mix so that one part qualifies the other; to qualify; to make fit; to unite in due proportion; to form to a proper degree of hardness, as metals; to soften; to mollify.