a grain of salt

(With) a grain of salt is a literal translation of a Latin phrase, (cum) grano salis. A pinch of salt may also be used.In common parlance, if something is to be taken with a grain of salt, it means that a measure of healthy skepticism should be applied regarding a claim; that it should not be blindly accepted and believed without any doubt or reservation. According to the Oxford English Dictionary "to take 'it' with a grain of salt" means "to accept a thing less than fully". It dates this usage back to 1647.
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