To interfere in a harmful manner: tried to tamper with the decedent's will; tampering with the timing mechanism of the safe.
To tinker with rashly or foolishly: Don't tamper with my feelings.
To engage in improper or secret dealings, as in an effort to influence: tamper with a jury. See Synonyms at interfere.
To alter improperly.
A neutron reflector in an atomic bomb that also delays the expansion of the exploding material, making possible a longer-lasting, more energetic, and more efficient explosion.