IPA: //ˌmɛtrəʊˈsɛkʃuəl//
KK: /ˈmɛtroʊˌsɛkʃuəl/
A man who pays a lot of attention to his looks, grooming, and fashion, often living in a city and having a good income.
He is a metrosexual who spends hours getting ready for a night out.
Metrosexual is formed from "metro-" (derived from the Greek "metropolis", meaning city) and "sexual" (from Latin "sexualis", meaning relating to sex or gender). The term describes a man, particularly in urban areas, who is preoccupied with his appearance and lifestyle, often associated with fashion and grooming.
Think of 'metro' as relating to the city, where many men are 'concerned with their appearance' ('sexual') — that's why metrosexual describes city men who care about their looks.