An Etymological Dictionary of Astronomy and Astrophysics

1. A long hollow cylinder of metal, glass, rubber, or other material used to transport or contain liquids or gases.
   

2. An electronic device in which electrons operate in a gas or in vacuo inside a closed envelope.

Etymology (EN): M.E., from M.Fr. tube, from L. tubus “tube, pipe,” of unknown origin.

Etymology (PE): Lulé “tube, pipe; roll,” dialectal Lori, Laki lil, Laki lul “wanderer;” Hamadâni lul “spiral, coil.”