In principle it means "joyful, funny", and for these characteristics it began to be used in Hollywood as a euphemism to name homosexual in cinema. In a short time it became popular around the world, as it is not necessarily discriminatory or pejorative (yet, in historically intolerant societies it is preferred not to use it in public to avoid misinterpretations). The etymological origin is very ancient, it comes from the languedoc (Roman Gaul, now south of France) where gai meant "joyful, festive", which in English came first as a cultured and literary voice. In Spanish it differs gay (homosexual) from gay (cheerful, poetic).
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