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Definition of Glow tube
1. Noun. A gas-discharge tube consisting of a cold cathode and a diode in a tube filled with gas; the color of the glow depends on the particular gas. 
Generic synonyms: Gas-discharge Tube
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1. Noun. A gas-discharge tube consisting of a cold cathode and a diode in a tube filled with gas; the color of the glow depends on the particular gas.