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.

An impudent or obnoxiously self-assertive individual, a wise guy, as in New teachers often have a hard time coping with the smart alecks in their classes. This expression, dating from the mid-1800s, probably alluded to a person of this description who was named Alec or Alexander, but his identity has been lost.

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.

A cocky individual who thinks he or she knows everything and is not shy about saying so. The origin of this term, an American colloquialism from the 1860s, has been lost; no one knows who that first Aleck (or Alexander) was. The adjective smart in the sense of “impudent” is much older (fifteenth century) but has died out except in this expression. Budd Schulberg used it in What Makes Sammy Run? (1941): “He’s a smart aleck. I can see already he thinks he knows more than I do.”