In Star Trek: The Next Generation, the Enterprise-D's main forward energy armament is a phaser array.
The Galaxy-class Enterprise-D carries long strips of phaser emitters built into the saucer and engineering sections. These arrays can direct energy into focused beams and can fire in multiple directions, giving the ship broader coverage than a single fixed weapon.
Star Trek uses “phaser” for a family of directed-energy weapons, from hand phasers to starship-mounted systems. The Enterprise-D's ship-wide arrangement is specifically called a phaser array. Its other major weapons include photon torpedoes, which are projectile-like antimatter weapons rather than energy beams.
A common mix-up is calling every Star Trek energy weapon a phaser. Klingon and Romulan ships commonly use disruptors, while Federation starships use phasers. The question concerns the Enterprise-D's principal beam weapon, not its torpedo launchers or defensive shields.