If you've ever talked about drag, camp, butches, and/or trade, you know at least some words from Polari, a secret gay language adopted by gay men in the United Kingdom between the 1920s and the 1960s.

You probably know what it means to “come out” as gay. You may even have heard the expression used in relation to other kinds of identity, such as being undocumented. But do you know where the term ...