two-decker I. \ˈ ̷ ̷| ̷ ̷ ̷ ̷\noun (-s) 1. a.: a ship with two decks b.: an old-time warship with guns on two decks 2.: something (as a bus) having two levels or layers II. adjective : having two decks, levels, layers, or classifications < a two-decker bus > < a two-decker tariff > : double-deck