Con definition: In opposition or disagreement; against. Comic-Con is dedicated to creating the general public’s awareness of and appreciation for comics and related popular art forms. The meaning of CON is something (such as a ruse) used deceptively to gain another's confidence; also : a confidence game : swindle. How to use con in a sentence. A con is a trick in which someone deceives you by telling you something that is not true. CON definition: 1. to make someone believe something false, usually so that that person will give you their money…. Learn more. The word con is commonly used to refer to a trick or act of deception, often to cheat someone out of money or confidence. It can also signify a disadvantage when weighing options, as seen in the phrase pros and cons. A con, or confidence game, is a swindle — when you take advantage of someone's trust. If you con someone out of their life savings, you might wind up a con — as in convict. A con, or confidence game, is a swindle — when you take advantage of someone's trust. If you con someone out of their life savings, you might wind up a con — as in convict. Con Edison bought it in 1954, and now operates the largest commercial steam system in the world, providing steam service to nearly 1,600 commercial and residential establishments in Manhattan from Battery Park to 96th Street. Of, relating to, or involving a swindle or fraud: a con artist; a con job. [Short for confidence.].