Definition of "upsetter" in English

noun

1. One who upsets (something); a disrupter.

   • And so were all Christians in Pliny's time, insane like others, and called not long after, followers of madness, upsetters of men, vicious innovators […]

2. A person or device that turns something upside down.

3. (metalworking) A kind of forging machine that moves horizontally.