Either talking excessively about something, or feeling exhausted and out of breath; in slang, to be impressed or excited.
From 'gas' (from Greek 'chaos' meaning void), originally meaning to talk nonsense. Later developed British slang meanings of exhaustion and excitement in different contexts.
Different English-speaking countries use 'gassed' completely differently—Brits say someone's 'gassed' when tired, Americans use it for excitement, showing how the same word evolves into opposite meanings based on regional isolation.
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