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quizá, quizás (Adverb) "maybe," "perhaps"

12th cent. Old Spanish quiçab. Probably from the Latin phrase qui sapit "who knows." Unfortately qui sapit does not give us quiçab or quizá but **quisá(b)! To remedy this difficulty, González Ollé (1981) hypothesizes a local Latin phrase qui id sapit "who knows it" must have existed. For the etymology of qui, see quien; for the etymology of sapit (3rd pers. sing. of sapere "to know") see saber.

Romance: Western Vulgar Latin: Portuguese quiçá, Italian chissà

Originally just quizá. Quizás was created by analogy with other adverbs ending in -s in the 16th cent.