fancy-pants

the term is a humorous american compound from the late 19th century, originally used literally to describe overly ornate trousers. the word 'fancy' evolved from the concept of imagination and fantasy into denoting things decorative or elaborate. 'pants' derives from the garment worn by the pantaloon character, a foolish old man, which became the general term for trousers. the compound metaphorically transferred from literal ornate clothing to describe people or things perceived as ostentatious or pretentiously sophisticated, capturing a mildly mocking tone towards affected elegance.

Structure: fancy (decorative, elaborate) + pants (trousers) fancy (from middle english 'fantsy', a contraction of 'fantasy', ultimately from greek 'phantazein' meaning 'to make visible'; functions as an adjective meaning decorative or elaborate). pants (shortened from 'pantaloons', from italian 'pantalone', a character in commedia dell'arte; functions as a noun meaning trousers).