This was a tricky one. The Latin word "tempus" means "time," and is the ancestor of such time-related words as "contemporary" and "temporary." So how did a word for stormy weather develop from a word meaning "time"? An important way of measuring time is according to the season, a method people frequently relied on long ago. And an important feature of the various seasons is the weather. Some seasons are notable for bringing extreme weather. From "tempus," Latin-speakers created a word that brought all of these ideas together: "tempestus," which means "season," "weather," and "storm." "Tempestus" came into English via Anglo-French as "tempeste," meaning "a violent storm," and eventually became the modern word "tempest."