smarty-pants

the term 'smarty-pants' is a 20th-century american english colloquialism, a classic example of a playful, mildly insulting compound. it builds upon the earlier term 'smarty' (attested from the late 19th century), itself an informal and often derogatory agent noun from 'smart'. the addition of '-pants' is a nonsense suffix, a common feature in english rhyming or jocular compounds (e.g., 'fancy-pants', 'lazybones'). the 'pants' element adds a humorous, infantilizing, or trivializing effect, softening the insult while mocking the target's perceived know-it-all attitude. the logic moves from the core idea of 'cleverness' to a specific, socially marked type of person who displays that cleverness in an ostentatious and irritating manner.

this is a compound word formed from two English lexical items. 'smarty' is a colloquial noun derived from the adjective 'smart' (meaning intelligent or clever, often with a connotation of impertinence). 'pants' is the plural noun for trousers. the compound functions as a single lexical unit.