The world of World Trigger is full of terms that are vital in understanding the basic plot.
Errant Nation: A planetary nation that doesn't follow a fixed orbit.
Neighbor: Inhabitants of the Neighborhood.
Neighborhood: The other dimension where Neighbors come from.
Operator: The person who watches and advises combatants on their team during battle.
Planetary Nation: A nation that is run on a single planet.
Rank Battles: Mock battles between Border combatants to earn points and increase their ranking.
Trigger: A technology that runs on trion.
Trion: The special form of energy found in every human and used to power Triggers.
Trion Soldier: Drones powered by trion, typically used for attacking, scouting, and kidnapping, among other uses.