Home › Words › U › undermateundermateundermate means A junior officer on board a ship.Among words judged in Lexicurio's Arena, undermate ranks #41,728 of 42,762 for Qualifying.EtymologyFrom under- + mate.nounA junior officer on board a ship.e.g.“Twice I actually hired myself as an under-mate in a Greenland whaler, and acquitted myself to admiration.” — 1816 June – 1817 April/May (date written), [Mary Shelley], Frankenstein; or, The Modern Prometheus. […], volume (please specify |volume=I to III), London: […] [Macdonald and Son] for Lackington, HugheDefinitions & examples from Wiktionary (CC BY-SA 3.0).