noun

• (military, nautical, historical) A battleship, especially of the World War I era, in which most of the firepower is concentrated in large guns that are of the same caliber.
  "Perturbed at being overtaken, the USS Texas is leading the 6th Battle Squadron at 22-and-a-half knots as the engineers pour everything they have into the effort. Behind the colossal clouds of smoke and cinders they put out come a seemingly-endless stream of dreadnoughts, battle flags flying from every mast and line they can find. It is the Grand Fleet."
• (military, nautical, historical) A battleship, especially of the World War I era, in which most of the firepower is concentrated in large guns that are of the same caliber.
  "Sovereign is the flagship of the rogue Spectre Saren. An enormous dreadnought larger than any other ship in any known fleet, Sovereign is crewed with both geth and krogan. At two kilometers long, its spinal-mounted main gun is likely capable of penetrating another dreadnought's kinetic barriers with a single shot."
• (by extension) One that is the largest or the most powerful of its kind.
  "Herbert steering the dreadnought limousine through the night, black cap on his black head."
• (by extension) One that is the largest or the most powerful of its kind.