WordWeb Online

1. The act of altering something secretly or improperly
   - meddling

1. Play around with or alter or falsify, usually secretively or dishonestly
   "Someone tampered with the documents on my desk";
   - fiddle [informal], monkey
    
2. Intrude in other people's affairs or business; interfere unwantedly
   "Don't tamper in my affairs!";
   - meddle

Derived forms: tamperings

Type of: change of state, interfere, interpose, intervene, manipulate, step in

Encyclopedia: Tampering