Meaning

verb bring to a desired consistency, texture, or hardness by a process of gradually heating and cooling

verb harden by reheating and cooling in oil

verb adjust the pitch (of pianos)

originPartly from Middle English temperd, temprede, from Old English temprode, first and third person singular preterit of Old English temprian; and partly from Middle English tempred, i-tempred, from Old English ġetemprod. Equivalent to temper + -ed.

Etymology from Wiktionary, CC BY-SA 3.0