0 Definition

noun
0.
Wiktionary
The origin, starting point, or fixed reference point, especially for a measurement.
The 0 for the Celsius scale is 273.15 Kelvin.
Wiktionary

(electrical engineering) The off or low bit state.

If the NOT gate input is 1, the output is 0.
Wiktionary
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adjective
(aviation) Zero-zero, a term meaning no ceiling and no visibility.
Wiktionary
Synonyms: