[tube] n [F, fr. L tubus; akin to L tuba trumpet] (1651) 1: any of various usu. cylindrical structures or devices: as a: a hollow elongated cylinder; esp: one to convey fluids b: a soft tubular container whose contents (as toothpaste) can be removed by squeezing c (1): tunnel (2) Brit: subway b d: the basically cylindrical section between the mouthpiece and bell that is the fundamental part of a wind instrument
2. a: a slender channel within a plant or animal body: duct--compare fallopian tube b: the narrow basal portion of a gamopetalous corolla or a calyx with united sepals
3: inner tube
4. a: electron tube; esp: vacuum tube b: cathode-ray tube; esp: a television picture tube c: television
5: an article of clothing shaped like a tube "~ top" "~ socks" -- tubed adj -- tube.like adj -- down the tube or down the tubes : into a state of collapse, deterioration, or ruin