It is very important to know little of the basics, so let's do a refresh, shall we?
Fashion:
1. A prevailing custom or style of dress, etiquette, socializing, etc.: the latest fashion in dresses.
2. Conventional usage in dress, manners, etc., esp. of polite society, or conformity to it: the dictates of fashion; to be out of fashion.
3. Something, such as a garment, that is in the current mode
4. The style characteristic of the social elite.
Fashion Arbiter:
1. Someone who popularizes a new fashion.
Fashion Designer:
1. Someone who designs clothing.
Fashion Roadkill
1. A person who tries to dress fashionably, but looks ridiculous (slang)
Fashion Victim:
1. You. No im kidding. An informal way of describing a person who follows every clothing trend.
Fashion-monger:
1. One who studies the fashions
Fashionable:
1. Observant of or conforming to the fashion; stylish: a fashionable young woman.
2. of, characteristic of, used, or patronized by the world of fashion.
3. current
Fashioner:
1. A person who fashions, forms, or gives shape to anything.
2. A tailor or modiste.
Fashionist:
1. An obsequious follower of the modes and fashions.
Fashionista:
1. A very fashionable person, esp. one who works in the fashion industry.
Fashionless:
1. Having No Fashion.
Source: Dictionary.com