Green’s Dictionary of Slang

1. a dupe, a fool; thus lit. the fool’s head; also found in 19C as cod’s head and shoulders.

1549		T. Chaloner (trans.) Erasmus Praise of Folie (1509) 83: But this notwithstandyng, the other coddes heddes in the meane while stande moste pleasauntly in theyr owne grace, or verilier stroke theim selues on the head.
1566		G. Gascoigne (trans.) Supposes II i: He that fisheth for him might be sure to catch a cod’s head.
1575		Appius and Virginia in Farmer (1908) 12: You cod’s-head, you crack-rope, you chattering pie.
1589		Nashe Death and Buriall of Martin Mar-Prelate in Works I (1883–4) 201: Play still the desperate and shameles Swadds as you haue begonn; for you couch your Coddheads.
1595		‘W.S.’ Lamentable Tragedie of Locrine III iv: Why then, goodman cods-head, if you will haue none of me, farewell.
1606		J. Day Ile of Guls II i: Will the Cods head bite?
1611		Fletcher Four Plays in Works of Beaumont & Fletcher (1912) X 300: Sweet Corporall codshead, no more standing on your punctilio’s and punketto’s of honor.
1623		Dekker Wonder of a Kingdom I ii: No fish bites at the baite of my poore beautie, but this tough Cods-head?
1624		Massinger Renegado III iv: Prethee let’s haue some sport, With this fresh Codshead.
1659		Greene & Lodge Lady Alimony V iii: Barren, you cods-head!
1665		Head Eng. Rogue I 325: This struck my young Gentleman as mute as a Cods-head.
1675		Woman Turn’d Bully II i: Farewell, Cods-head.
c.1700		London-Bawd (1705) 3: Of a Countrey-Gentleman she makes a Cods-head.
1714		N. Ward Miseries of Whoring 158: The codsheads shall / Out of their wonton Understanding call / This young Man to that Post of trust and care.
1725		New Canting Dict.
1737, 1759, 1760, 1776		Bailey Universal Etym. Eng. Dict.
1762		Bridges Homer Travestie (1764) II 101: O warriors! cries this head of cod, / I’ll smoke great Hector’s hide, by g—d.
1772		Bridges Burlesque Homer (3rd edn) 288: [as cit. 1762].
1797		Bridges Burlesque Homer (4th edn) II 232: [He] / Gave his cod’s head a mighty shake.
1812		‘Hector Bull-us’ Diverting Hist. of John Bull and Brother Jonathan 65: She called him prating gabbler, liquorish glutton [...] codshead booby, noddipeak simpleton, ninnihammer gnatsnapper, and various other names.
1828		Edinbury Gleaner 55: Some are call’d Cod’s heads, wanting brains.
1831		Satirist (London) 30 Oct. 235/2: This learned dissertation was suddenly put a stop to, by poor Codshead [a fishmonger] putting his hand in his pocket for his handkerchief, and drawing forth his blue apron.
1834		‘Jack Downing’ Andrew Jackson 33: It needed somethin more than a cod’s-head to manage, with such leger-de-main and hocus-pocus.
1851		R.S. Surtees Young Tom Hall (1926) 218: She thought him a queerish-looking, cod’s-head-and-shoulders little man.
1853		Dickens Bleak House (1991) 79: ‘Why, what a cod’s head and shoulders I am,’ said Mr. Jarndyce.
1868		‘The Stirabout Pot’ My Young Wife and I Songster 38: Oh, my cod’s head’s stewing in her pot.
1899		Cornishman 27 July 6/2: Ben, clodpate, cod’s-head, corky-brained [...] are all synonyous, in the language of the canting crew, for fool.
1914		Sport (Adelaide) 1 May 4/2: [as a nickname] They are waiting for Codshead W to return.

2. see cod n.³