step on

verb5

1. •
   To oppress or mistreat (a person).

   • He had been stepped on so many times he just didn't even get angry anymore. — 1985
2. •
   (slang) To intrude on someone else's turf or portfolio.

   • They're stepping on our operations.
3. •
   To adulterate (a drug) for the purpose of increasing its bulk, and therefore the profit when sold; to dilute, cut.

   • This seems implausible. If ecstasy is going to be stepped on, you'd dilute it with something cheaper than heroin. — 1994
4. •
   To interrupt, overpower, or override (another transmission on the same frequency) with one's own transmission.
5. •
   (old-fashioned) To approach as to confront or fight.

   • He stepped on to the vicious man.