A person who immediately supports either physically, vocally, or interactively a cause or movement on the merit of how they feel about an issue or incident before all the facts surrounding the galvanizing issue or incident are completely known.
He was enraged at the apparent lack of concern for the feelings of those offended and immediately joined other reactivists on social media posting to get the offending party censured.
by Gramaticus November 11, 2015
A portmanteau of "Reactive Activist," refers to a person that expresses a knee-jerk reaction to a perceived issue that they know of solely because it was brought to their attention; either by pop culture osmosis or explicitly brought to them. The issues they bring up are usually missing context that the Reactivist is either unaware of or refuses to research out of fear of being wrong. This is sometimes to get attention, but usually is because it's easier to give a hot take on social media than make an informed opinion.
by dirtwashere December 5, 2021