Definition of ship of the line in US English:

ship of the line

noun

historical
  • A sailing warship of the largest size, used in the line of battle.

    • ‘Ships of sixth rate and above were of sufficient size to qualify as ships of the line in naval battle.’
    • ‘Inside, the library has something of the sober, purposeful and hand-crafted feel of a ship of the line of Nelson's time.’
    • ‘A ship of the line carried up to a thousand men, most of whom were gunners only needed in battle.’
    • ‘The basic unit of sea power was the ship of the line or battleship, mounting a minimum of 40 or 50 guns, and 100 or more, capable of taking its place in the line of battle.’
    • ‘But the harbour was not good enough for the Royal Navy with their mighty ships of the line.’