tube [tju:b] noun 1. [hollow cylinder - inflexible] Röhrchen das, Rohr das [ - flexible] Schlauch der 2. ANAT (bronchial)tubes Bronchien pl 3. [of toothpaste, glue] Tube die 4. (UK) [underground train] U-Bahn die [underground system] the tube die U-Bahn (phrase) by tube mit der U-Bahn