In Delia, a transient railway worker. See OED. ("Come all you rounders, for I want you to hear..." Casey Jones, a 1908 version in the Railroad Man's Magazine).
Now, in the USA and Canada, mostly has the sense of an habitual carouser.

Of course several other meanings, as shown above, depending on context.
In the 1850s, a gladhander ('glover').

(In the 1600s, another name for Puritan (roundhead).