What is described as "a line used for towing or mooring"?

The term that describes "a line used for towing or mooring" is hawser. A hawser is specifically a heavy-duty line, typically made of fiber or synthetic materials, designed to bear significant loads during towing or securing vessels. These lines are utilized in both nautical contexts for mooring ships at docks and for towing them across bodies of water.

While "line" is a more general term that can refer to any kind of rope or cable, and "cable" often indicates a type of line that is strong and usually made of metal, neither captures the specific function and robust nature of a hawser as it pertains to towing and mooring. "Rope" can also refer to various types of lines used for different purposes, but it lacks the specific application that a hawser implies in maritime operations. Thus, the designation of hawser most precisely describes a line with the capacity and purpose intended for towing or mooring activities.