A boutique is "a small store that sells stylish clothing, jewelry, or other usually expensive things".The word is french for shop which derives ultimately from the greek  ἀποθήκη (apothēkē) or "storehouse"
The term "boutique" entered into everyday English in the late 1960s when, for a brief period, London was a fashion capital. Carnaby street and kings road(London)  were the focus of much of media attention for having the most fashionable stores of the era.