a smart alec

smart alec(k)

One who makes jokes and uses sarcasm in an attempt to seem witty, but instead is deemed annoying. I'd had enough of that smart aleck's wisecracks, so I left the party early. Don't be such a smart alec, Sally.
See also: smart
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.

a smart alec

BRITISH or

a smart aleck

A smart alec or a smart aleck is someone who is very clever and who is often able to answer questions in a clever way. Note: People sometimes spell `alec' and `aleck' with capital initials, as names. They've got some smart alec of a lawyer from London to oppose bail. Note: You can use smart alec and smart aleck before a noun. I hate smart-aleck kids who talk like dictionaries. Note: You use this expression to show that you find someone annoying. Note: Alec or Aleck is a shortened form of the name Alexander.
See also: alec, smart
Collins COBUILD Idioms Dictionary, 3rd ed. © HarperCollins Publishers 2012

a ˈsmart alec/aleck

(informal, disapproving) a person who tries to show that they are cleverer than everyone else: Some smart alec wrote in to say that the last edition of the newspaper contained 37 printing errors.
See also: alec, aleck, smart
Farlex Partner Idioms Dictionary © Farlex 2017
See also:
References in periodicals archive ?
I know he was trying to help but sometimes empathy can come across as just being a smart Alec.
He branded it "a Smart Alec title" for a "Smart Alec article" and said it was a "lousy" thing to do to his client.
If a Smart Alec is someone who is clever, what does that make you lot?
I'm not being a smart Alec here but, just in case you ever pass the same train, it was Gianfranco who played for Chelsea.