merchant marine

merchant marine (plural merchant marines)

1. (countable) Synonym of merchant navy: a fleet of commercial vessels.
2. (countable) Synonym of merchant ship: a single vessel in such a fleet.
   • 1923 May 28, “Captain Dollar Speaks”, in Time:

     Captain Robert Dollar of San Francisco, dean of American ship owners, […] is still, although nearly 80, the eager champion of an American privately owned merchant marine.

3. (countable, proscribed, nonstandard) Synonym of merchant mariner: a sailor in such a fleet.

• The merchant mariner sense is a catachresis born of misconception, influenced by the notion that as a marine is a naval infantryman, a merchant marine would be a single commercial sailor; thus come catachrestic phrases such as he joined the merchant marines [sic]. But the sense is common enough that it is often accepted politely without objection in casual conversation.