A trick or deception, especially one used to cheat someone out of money. The con artist was arrested for running a con on unsuspecting tourists.
A convict, especially one who is serving a prison sentence. The con was released on parole after serving five years in prison.
An argument or consideration against something. The cons of the new policy were discussed at the meeting.
A convention, especially one for fans of comics, science fiction, gaming, etc. More than 50,000 people attended the anime con last summer.