Merchant marine and Old salt

Merchant marine noun - Conveyance provided by the ships belonging to one country or industry.

Old salt and merchant marine are semantically related. In some cases you can use "Old salt" instead a noun phrase "Merchant marine".

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

Merchant marine and old salt are semantically related. Sometimes you can use "Merchant marine" instead a noun phrase "Old salt".