What is the definition of mongerers?

Answer 1

A "monger" is someone who is a big proponent (fan, supporter) of something. These days it is most commonly used when speaking of someone who is very enthusiastic about declaring war--referred to as a "warmonger" or is trying to stir up a war--"warmongering."

However, in the past the term could be attached to almost any noun and give the idea that the person dealt exclusively with that thing--a fishmonger, for example, sold fish. An ironmonger dealt with iron products--traded, sold, or made them.