Definition of smart-alecky in US English:

smart-alecky

adjective

informal
  • Denoting or characteristic of a person who behaves as if they know everything.

    ‘he seemed a vain, smart-alecky academic’
    ‘the smart-alecky tone can grate a little’

Pronunciation

smart-alecky

/ˈsmärdˈaləkē//ˈsmɑrdˈæləki/