Definition of lubber's line in English:

lubber's line


(also lubber line)
  • A line marked on the compass in a ship or aircraft, showing the direction straight ahead.

    ‘Adjustable compasses have a compass body with a lubber's line and a rotating capsule or bezel with a boxing mark.’
    • ‘Simple compasses may use north or 0º on the azimuth circle as a lubber's line.’