conduit consisting of a long hollow object (usually cylindrical) used to hold and conduct objects or liquids or gases | a thermionic vacuum tube having three electrodes; fluctuations of the charge on the grid control the flow from cathode to anode which makes amplification possible |
an electric railway operating below the surface of the ground (usually in a city) | |
electronic device consisting of a system of electrodes arranged in an evacuated glass or metal envelope | |
(anatomy) any hollow cylindrical body structure | |
a hollow cylindrical shape | |