1. Formerly, a kind of naval cadet, in a ship of war, whose business was to carry orders, messages, reports, etc, between the officers of the quarter-deck and those of the forecastle, and render other services as required. In the english naval service, the second rank attained by a combatant officer after a term of service as naval cadet. Having served three and a half years in this rank, and passed an examination, he is eligible to promotion to the rank of lieutenant.
2. (Science: zoology) An American marine fish of the genus Porichthys, allied to the toadfish. Cadet midshipman, formerly a title distinguishing a cadet line officer from a cadet engineer at the U. S. Naval academy. See Cadet. Cadet midshipman, formerly, a naval cadet who had served his time, passed his examinations, and was awaiting promotion; now called, in the united states, midshipman; in England, sublieutenant.