'smart-aleck' originates from American English, specifically the nickname 'Smart Alec' (an informal name used in the 19th century).

'Smart Alec' referred initially to a particular nickname (possibly of a gambler or con man named Alec or Alexander) and then became generalized into the noun and adjective forms 'smart-aleck' and 'smart-alecky' in common usage.

Initially it referred to a specific nickname or individual ('Smart Alec'), but over time it evolved into the general meaning 'an irritatingly clever or impertinent person.'