"agendaposter" means: Someone who consistently frames their social media content around advancing a particular ideology, grievance, or political angle while maint.... This is a fairly neutral word with no inherent risk attached. There is no real cause for parental concern; it is descriptive vocabulary rather than something dangerous. If your child uses it, context will usually make the meaning clear. A brief, curious question about where they heard it is generally enough to know whether to follow up.