Definition of "mazard"

Why ee'n ſo: and now my Lady Wormes, / Chapleſſe, and knockt about the Mazard with a Sextons Spade;

c. 1599–1602 (date written), William Shakespeare, “The Tragedie of Hamlet, Prince of Denmarke”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, [Act V, scene i], page 277

This roused the tinker's choler, already provoked at Tugwell's amorous freedom with his doxy, and he gave him a click in the mazard. Tugwell had not been used tamely to receive a kick or a cuff; he, therefore, gave the tinker a rejoinder, […]

1808, Richard Graves, The Spiritual Quixote, page 127

For the poor things [worshippers] would have other idols in place of those he [the iconoclast] thwacketh upon the mazzard and dispelleth.

1906, Ambrose Bierce, “Iconoclast”, in The Cynic’s Word Book, London: Arthur F. Bird […], page 170