Old salt and Shipmate

Old salt noun - A man who serves as a sailor.

Shipmate and old salt are semantically related in sailor topic. In some cases you can use "Shipmate" instead a noun phrase "Old salt", when it comes to topics like person who travels by sea.

Shipmate noun - An associate on the same ship with you.

Old salt and shipmate are semantically related in sailor topic. You can use "Old salt" instead a noun "Shipmate", if it concerns topics such as person who travels by sea.