Definition of "blockhead"

So I think, blockheads, said Manfred: what is it has scared you thus?

1764, “Onuphrio Muralto”, translated by William Marshal [pseudonym; Horace Walpole], The Castle of Otranto, […], Dublin: […] J. Hoey, […], published 1765

[…] like a conceited mechanic in a village ale-house, you would set down every one who differs from you as an ignorant blockhead […]

1819, William Hazlitt, “A Letter to William Gifford, Esq.”, in A. R. Waller, Arnold Glover, editors, The Collected Works of William Hazlitt, volume 1, London: J. M. Dent & Co., published 1902, page 368

"What a blockhead that Charlie Brown is!"

1953, Charles Schulz, Peanuts

Not all of them, by no means anywhere close to all of them, just the most notable blockheads among them — three altogether, two freshmen and one sophomore, all of whom were among the first to be expelled the next day — masturbated into pairs of stolen panties […]

2008, Philip Roth, Indignation

Waldo was sent that from an elderly blockhead named Fuzzy in Gibtown, Florida. That's the town to which most freaks retire.

2005, Brian M. Wiprud, Stuffed, page 262

He is a classic sideshow performer, entertaining crowds with feats such as sword swallowing, fire-eating, and chainsaw juggling. His specialty, however, is the human blockhead act, hammering six-inch nails up his nostrils.

2014, Louis J. Parascandola, John Parascandola -, A Coney Island Reader: Through Dizzy Gates of Illusion, page 306

Burkhardt was a legendary figure in the sideshow world, a mentor and instructor to a new generation of blockheads and other working acts who now train in private classes at Coney Island USA's Sideshow School with Burkhardt's disciple Todd Robbins (Zigun 2006).

2016, M. Chemers, Staging Stigma: A Critical Examination of the American Freak Show

Like an old-time sideshow, the acts included lying on a bed of nails, blockheading and, of course, fire-eating.

2007, Frank Cullen, Florence Hackman, Donald McNeilly, Vaudeville old & new: an encyclopedia of variety performances in America

Two years' blockading made fair Malta ours: A noble struggle! -- yet 't is thought (at Rading) That Britain's island shews superior pow'rs, To bear, and to survive, two years blockheading !

1804, The Spirit of the Public Journals

I have blockheading and boxing enough at Master Lovell's, I won't have it repeated here; and in a great passion, I threw the Virgil at his head, hit him in the face, and bruised his lip, and ran away.

1856, John Adams, The works of John Adams, second President of the United States

The operation of blockheading is much the same as that of beheading, which Charles I underwent. In both the head is severed from the body. The body goes around without benefit of head. The victim becomes a Headless Horseman, or that more common figure a Headless Pedestrian. In our day the operation is often done not on an executioner's block but on Paradise Avenue in Suburbia Manor.

1958, The Ethical Outlook: A Journal of the American Ethical Union