tam•perˈtæm pər(v.i.)

1. to meddle, esp. in order to alter or misuse (usu. fol. by with):

   to tamper with a lock.

2. to make changes, esp. in order to falsify (usu. fol. by with):

   to tamper with official records.

   Category: Common Vocabulary

3. to engage secretly or improperly in something.

4. to engage in underhand dealings, esp. in order to influence improperly (usu. fol. by with):

   to tamper with a jury.

   Category: Common Vocabulary

Origin of tamper:

1560–70; appar. dial. alter. of temper (v.)

tam′per•er(n.)