fancy-pants

Short definition from Wiktionary

Noun

1. 1
   Alternative spelling of fancy pants.
2. 2
   Someone fancy, silly or attractive.
3. 3
   A person wearing fancy clothing; a member of a social elite.
4. 4
   A person very concerned with their appearance.

Adjective

1. 1
   overly fancy with little function; newfangled; complicated