Definition

Adverb 1. At right angles to the length of a ship or airplane: This term describes a direction or position that is perpendicular to the centerline (the line from the front to the back) of a vessel or aircraft. It is a nautical and aeronautical term used to indicate something is directly to the side, at a 90-degree angle from the direction of travel.

Usage Examples

• Adverb:
  • The lighthouse was directly abeam of our ship. (The lighthouse was positioned exactly to the side, at a right angle to our ship's length.)
  • The pilot reported another aircraft flying abeam to our left. (The pilot reported another plane flying parallel and directly to our left side.)
  • We sighted land when the island was abeam. (We saw the land when it was positioned off our side.)

Advanced Usage

• "Abeam of": This is the most common construction, used to specify the object that is positioned to the side.
  • The buoy is abeam of the starboard side. (The buoy is directly to the right side of the vessel.)
• Used as a positional reference: In navigation, "abeam" is a precise term for reporting bearings or locations relative to the vessel's heading, often used in commands or observations.
  • "Enemy ship sighted, two points abaft the starboard beam!" (This uses "abeam" as a root concept for the positional term "beam," meaning the side of the ship.)

Variants and Related Words

• Beam (noun): The side of a ship. "Abeam" literally means "on the beam."
• Abaft the beam (phrase): A direction behind a line drawn perpendicular to the ship's side.
• Forward of the beam (phrase): A direction in front of a line drawn perpendicular to the ship's side.

Synonyms

• Aboard the beam: A less common synonym with the same meaning.
• On the beam: Essentially synonymous, though sometimes used more broadly.
• Athwartships: A technical term meaning across the ship from side to side, often relating to direction or structure rather than a relative position of an external object.

Related Phrases

• Broad on the beam: Directly or exactly abeam.
  • The other vessel is broad on the port beam. (The other ship is directly to the left side.)

Notes on Meaning

This word is highly specialized and is almost exclusively used in the contexts of maritime navigation and aviation. Its core meaning is strictly geometric, referring to a 90-degree angle relative to the fore-and-aft line. It does not describe distance, only direction.

Adverb

1. at right angles to the length of a ship or airplane