Mrs T was a roundhead politician, but she was no republican.
From the guardian.co.uk
Roundhead and Cavalier, a rivalry that seemed fated.
From the time.com
He may be the roundhead to O'Sullivan's cavalier, but the Masters champion is tipping his rival to have another excellent run.
From the express.co.uk
England's many Puritans and Presbyterians were almost invariably roundhead supporters, as were many smaller religious groups such as the Independents.
From the en.wikipedia.org
Anglers drop roundhead jigs tipped with minnows or artificial baits and try to keep the line straight up and down in the current as they work the jigs within a foot or so of the bottom.
From the freep.com
More examples
A brachycephalic person
A supporter of parliament and Oliver Cromwell during the English Civil War
The longfins also known as roundheads or spiny basslets are a family, Plesiopidae, of fishes in the order Perciformes. They are elongated fishes, found in the Indian Ocean and western Pacific Ocean.
A roundhead was a type of mace used during the English Civil War. It is described as having a head about nine inches long, a staff two yards long inserted into the head, twelve iron spikes round about, with another spike in the end. ...
(The Roundheads (Doctor Who)) The Roundheads is a BBC Books original novel written by Mark Gatiss and based on the long-running British science fiction television series Doctor Who. It features the Second Doctor, Ben, Jamie, and Polly.
A roundhead screw, one with a domed head; Describing the head of a screw that is dome shaped
(Roundheads) Soldiers of the New Model Army, so called because of their closely cropped hair (see Cavaliers, above).
(Roundheads) Supporters of Parliament in its dispute with Charles I concerning exercise of the royal prerogative and in the Civil War. ...
Noun. A circumcised penis and consequently a male with such. Cf. 'Cavalier'.