Definitions
1.VerbTo adulterate (a drug) for the purpose of increasing its bulk, and therefore the profit when sold; to dilute, cut.
2.VerbTo oppress or mistreat (a person).
3.VerbTo interrupt, overpower, or override (another transmission on the same frequency) with one's own transmission.
4.VerbTo approach as to confront or fight."He stepped on to the vicious man."
5.VerbTo intrude on someone else's turf or portfolio."They're stepping on our operations."
6.VerbUsed other than figuratively or idiomatically: see step, on."He stepped on a rock."