A twister is any twisting object or being. In informal usage, the word refers to a tornado or whirlwind. In informal British English, to call someone a twister is to say that she is a dishonest and unprincipled person.
Historical records show that the word "twister" was in English usage by the 16th century. Speakers of American English started calling tornadoes or whirlwinds twisters by the last decade of the 19th century. The 1996 Hollywood film "Twister" was about violent tornadoes. The word has yet another denotation; in the slang of the American criminal underworld, a twister is a key.