A plasma spread was a type of weapon used by some species in the Alpha Quadrant. An omnidirectional burst of plasma was projected from the weapon's emitter, creating an energetic wave that was nearly impossible to evade or defend against. The weapon is most useful when used against multiple small targets, because it allows the user to attack several targets at once.
The Ferengi D'kora-class marauder was equipped with plasma spreads, as was the Cardassian missile later known as Dreadnought. (TNG: "The Last Outpost", VGR: "Dreadnought")