slang An honest, respectable, and law-abiding woman. Used primarily in criminal and prison communities. You really shouldn't get involved with a square-john broad. You'll be spending all your time avoiding her questions so she won't know what you really do for a living. We'll get Tommy's cousin to make the drop for us. The security guards wouldn't bat an eye at a square-john broad like her.
See also: broad
square john broad
n. an honest, straightforward woman. (Underworld.) We need a square john broad to give this place a look of respectability.