n (US|Canada|automotive) The luggage storage compartment of a sedan/saloon style car.
n (US|telecommunications) A circuit between telephone switchboards or other switching equipment.
n a chute or conduit, or a watertight shaft connecting two or more decks.
n (context|software engineering, jargon) in software projects under source control: the most current source tree, from which the latest unstable builds (so-called "trunk builds") are compiled.
n (transport) A main line in a river, canal, railroad, or highway system.