What is the meaning of tampering?

noun

• The act of altering something secretly or improperly.
  • synonyms: meddling

verb

• Play around with or alter or falsify, usually secretively or dishonestly.
  • usage: "Someone tampered with the documents on my desk"; "The reporter fiddle with the facts"
  • synonyms: tamper, fiddle, monkey
• Intrude in other people's affairs or business; interfere unwantedly.
  • usage: "Don't meddle in my affairs"
  • synonyms: meddle, tamper