A sex kitten is a woman who exhibits a sexually provocative lifestyle or an abundant sexual aggression. The term originated c. 1958, and was originally used to describe French actress Brigitte Bardot.
Ann-Margret was described as a sex kitten in the 1964 film Kitten with a Whip. A sex kitten is not always youthful.
References
Sex kitten Wikipedia(Text) CC BY-SA