0 the action of touching or making changes to something that you should not, usually when you are trying to damage it or do something illegal: --
He was concerned that the way she was investigating the case constituted obstruction of justice or tampering.
Any tampering with the system risks making it less effective.
The medications come in sealed containers to protect against tampering.
1 the illegal act of touching or making changes to something when you should not: --
A subeditor changed the names throughout the piece, and the newspaper later apologized to the author for the tampering.
The machines could be locked by officials when voting was over, preventing - or at least reducing - tampering.
The writer appeals to us to protect nature against human tampering.