Definitions

1. noun

A device used to protect a ship from attack, consisting of a chain or cable suspended between two points, often with iron arms or hooks to grapple enemy ships.

“The 18th-century warship deployed its blackarm to fend off the enemy fleet.”

2. noun

A type of medieval defensive structure, a fortified gatehouse with iron bars or a portcullis, often equipped with a murder hole.

“The castle’s blackarm was the only entrance that provided any level of security during the siege.”