alec
n. countablen. a person who acts like they know everything and tries to sound more clever than everyone else. It is almost always used in the phrase 'smart alec' to describe someone being a bit annoying or rude.
n. a person who behaves in a cocky or conceited manner, typically by making clever or sarcastic remarks. Almost exclusively used as part of the compound noun 'smart alec' (or 'smart aleck').
Don't be such a smart alec when I'm trying to help you.
The teacher grew tired of the smart alec in the back row who constantly interrupted the lesson with sarcastic jokes.
While his colleagues found his quick wit impressive, his tendency to play the smart alec during serious board meetings eventually hindered his chances for a promotion.
Clipping of Alexander.
Usually occurs in the fixed expression 'smart alec'; the spelling 'smart aleck' is also common.