[tam.per] vi tam.pered ; tam.per.ing [prob. fr. MF temprer to temper, mix, meddle--more at temper] (1567) 1: to carry on underhand or improper negotiations (as by bribery)
2. a: to interfere so as to weaken or change for the worse--used with with b: to try foolish or dangerous experiments--used with with -- tam.per.er n -- tam.per.proof adj