Green’s Dictionary of Slang

con-man n.

[con v. (1)]

1. [late 19C] (US) a flatterer.

2. [late 19C–1920s] (orig. US, also con guy, con player, con-woman) a confidence trickster [later use is SE].

3. attrib. use of sense 2.

4. [1930s] (US) a former convict.