tube train

== English == === Etymology === Probably named after the shape of the tunnels; the Tube is an informal name for London Underground which has been trademarked. === Noun === tube train (plural tube trains) (rail transport, UK) A smaller-profile underground train which operates through the tube tunnels under London, which have a small cross section. ==== Usage notes ==== Tube trains are operated on the Bakerloo, Central, Jubilee, Northern, Piccadilly, Victoria and Waterloo & City Lines. The trains that operate on the Circle, District, Hammersmith & City and Metropolitan Lines pass through larger tunnels and accordingly have a larger profile; these should be called underground trains, not "tube trains". === References === “tube train”, in Collins English Dictionary. === Anagrams === intratube, tribunate, turbinate