In the British civil war, the opposers to the king were called roundheads, because thier typical haircuts made thier heads appear round.
Roundheads! Cavaliers!
by Kung-Fu Jesus May 2, 2004
1. A circumcised penis
2. A circumcised man

cf Cavalier
"Is he circumcised?"
"Yeah, he's a Roundhead"
by satania April 8, 2005
A term used among rail workers in Melbourne Australia to describe a socially inept train enthusiast. Often abbreviated to "roundie".
Johnny is such a roundhead / Johnny is such a roundie.
by Captain Roundie December 13, 2013
A slang term used throughout New England and parts of Canada used to describe the phenomenon of Polish people who all seem to have unusually round heads.
"Yashoo has an extremely Round head, he is no doubt a ROUNDHEAD"
by Stash Leja November 12, 2004
used to identify a pole (or polack) in a crowd of people
The real winner is that roundhead over there.
by johnnieboy July 18, 2006
A reference to the look of the skull and face of people from Finland and the far north, artic circle, indigenous natives. As opposed to the square cranial shape of Swedes and Norwegians.
That roundhead is from Finland, he isn't a squarehead Swede.
by hawkinsson March 11, 2019
a fellow who is completely bald, or the head itself. So called because such a head looks round. Such guys may be labeled as nerds or outcasts, on account of their ugly heads.
Kenny,Kevin,Tom,Jamie,Matt,Robert,William,Uriah,Harun,and Jim all had their heads shaved,so now they're roundheads. They stink and look ugly,but as long as they're content,so be it.
by JMC70 November 29, 2016