midshipman

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A student training to be a commissioned naval officer, especially a student at a naval academy.
• noun Any of various toadfishes of the genus Porichthys found in coastal waters of the Americas, having several rows of light-producing organs along the sides of their bodies.

from The Century Dictionary.

• noun In 1902, Congress abolished the title of naval cadet in the United States navy and restored the title of midshipman. These officers are not commissioned officers, but receive appointments on probation, on the nomination of the President of the United States, of senators, or of congressmen, and the passage of an entrance examination to the Naval Academy. The course of instruction at the Naval Academy lasts four years and is followed by two years at sea, after which midshipmen are promoted to ensigns or second lieutenants of marines upon passing a final examination.
• noun A warrant officer in the British navy of the lowest grade of officers in the line of promotion.
• noun In the United States navy, formerly, an officer of corresponding rank and duties whose designation is now naval cadet.
• noun In ichthyology, a batrachoid fish, Porichthys margaritatus: so called from the rows of round luminous bodies along the belly, like the buttons of a naval cadet's coat.

from the GNU version of the Collaborative International Dictionary of English.

• noun 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.
• noun 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.
• noun In the United States navy, the lowest grade of officers in line of promotion, being students or graduates of the Naval Academy awaiting promotion to the rank of ensign.
• noun (Zoöl.) An American marine fish of the genus Porichthys, allied to the toadfish; also called singingfish.
• noun formerly a title distinguishing a cadet line officer from a cadet engineer at the U. S. Naval Academy. See under Cadet.
• noun 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.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun nautical An officer of the lowest rank in several navies; especially, a trainee officer.
• noun nautical, uncountable This officer rank.
• noun biology A midshipman fish.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a temporary rank held by young naval officers in training