Green’s Dictionary of Slang

dead as... adj.

used in a variety of phrs. meaning absolutely dead (see also combs. below).

[UK]N. Field Woman is a Weathercock IV ii: pouts.: Strange murdered on the wedding-day by you, At his own bride’s appointment, for my sake? strange.: As dead as charity.
[UK]Morris et al. ‘Knowing Joe’ Festival of Anacreon (1810) 52: I dropp’d down, dead as a shot.
[UK]Leicester Jrnl 4 Dec. 4/5: ‘Dead as a herring,’ he exclaimed, throwing down his gun.
[UK]R. Barham ‘The Grey Dolphin’ Ingoldsby Legends I (1866) 43: He was as dead as ditch-water!
[US]Spirit of Democracy (Woodsfield, OH) 19 Sept. 1/6: I let fly at the she bar [i.e. bear] [...] Over she rolled as dead as a mackerel.
[UK]Taunton Courier 3 Jan. 8/1: As live as a bird — as dead as a stone.
[UK]West Kent Guardian 19 Mar. 3/6: The herring is a delicate fish [...] hence the proverb ‘as dead as a herring’.
[US]F.H. Hart Sazerac Lying Club 68: They hung him as dead as a nit.
[US]C.F. Lummis letter 13 Nov. in Byrkit Letters from the Southwest (1989) 90: He was as dead as Adam is.
[US]Eve. Star (DC) 27 Oct. 4/2: Mr Wade [...] was dead as Abel.
[UK]Eve. Teleg. (Dundee) 19 Sept. 2/6: he threatened to fill the shopkeeper ‘as dead as a mackerel’.
[UK]Kipling Captains Courageous 4: Say, gen’elmen, this is deader ’n mud.
[Aus]Bulletin (Sydney) 26 Jan. 14/1: There was Dick swingin’ like a penjulum out in space, dead as a pick-head.
[UK]Marvel III 6: She’s as dead as a jint of hot roast beef!
[US]L.W. Payne Jr ‘Word-List From East Alabama’ in DN III:iv 304: dead as Hector, adj. phr. Entirely dead.
[US](con. 1917–18) T. Boyd Through the Wheat 199: ‘Where’s Lieutenant Bedford?’ [...] ‘Dead as hell,’ he was answered.
[US]J. Peterkin Scarlet Sister Mary 93: Why’n you bank de fire last night? E’s dead as a wedge.
[US]Z.N. Hurston Jonah’s Gourd Vine (1995) 7: Ah’ll knock yuh dead ez Hector.
[US]Z.N. Hurston Mules and Men (1995) 45: If he ever heard tell of him layin’ a whip on his hawse agin he was gointer take and kill John’s hawse dead as a nit.
[US]J.M. Cain Serenade (1985) 205: From some of them you get a beat as dead as an undertaker’s handshake.
[Aus]Morn. Bulletin (Rockhampton, Qld) 12 Sept. 6/3: Stand back or I’ll drop you as dead as a maggot. I will drop you cold.
[US]O. Strange Sudden Takes the Trail 35: They find him [...] with a couple o’ slugs in his back, dead as Moses.
[UK]A. Christie Murder Is Announced (1958) 114: Surely that’s dead as the hills.
[US](con. 1944) H. Robbins A Stone for Danny Fisher 299: This time yuh try an’ run me aroun’ an’ yuh’re deader’n hell.
[UK]M. Terry Old Liberty (1962) 113: The Communist Party is dead as a pumpkin in the U.S.
[Aus]J. Alard He who Shoots Last 59: Dey’re dead all right, dead as a Sunday school picnic.
[US]B. Greer Slammer (1977) 95: Stabbed him thirty times or so with screwdrivers. Deader than Swiss cheese.
[US]S. King Stand (1990) 238: You’ll be dead as dogmeat.
[UK]F. Norman Too Many Crooks Spoil the Caper 7: Dead as a nail in a coffin, Inspector. [Ibid.] 19: Louie was as dead as yesterday’s newspapers.
[US](con. 1968) D.A. Dye Citadel (1989) 125: The Goddam ricochets offa them dudes’ll kill you dead as dog shit.
[US]J. Wambaugh Secrets of Harry Bright (1986) 33: He’s deader’n gramma’s clit. [...] He’s deader’n John De Lorean’s MasterCard.
[US]S. King It (1987) 928: He’s just as dead as a fencepost.
[UK]K. Lette Llama Parlour 227: The guy [...] is as a dead as a mutton chop. He’s dead as a weekend in Dubuque.
Star (Jamaica) 13 Nov. [Internet] ‘We learnt from the hospital that she was there. When we arrived she was dead as nit’.

In phrases

...a doornail (also dead as a coffin nail, ...hangnail, ...nail) [SE doornail, the large-headed nails with which doors were studded for extra strength and protection; 17C+ use is SE]
[UK]William of Palerne 628: For but ich haue bote of mi bale I am ded as dorenail [OED].
[UK]Langland Piers Ploughman (1550) I Biii line 185: That Faythe is right nothing worth And as deade as a dore-nayl.
[UK]Shakespeare Henry VI Pt 2 IV x: If I do not leave you all as dead as a door nail, I pray God I may never eat grass more.
[UK]Nashe Praise of the Red Herring 47: Down she sunk to the earth, as dead as a doore naile, and neuer mumpt crust after.
[UK]R. Armin Nest of Ninnies 11: But now the thought of the new come foole so much moued him, that he was as dead as a doore-nayle.
[UK]Mennis & Smith ‘The Blacksmith’ Wit Restor’d (1817) 281: When you meet with naughty beere or ale, You cry it is as dead as a dore nayle.
‘Peter Aretine’ Strange Newes 1: Bonny Bette. [...] Is trading quick or dead? Moll. As dead as a dore nail.
[UK]C. Cotton Virgil Travestie (1765) Bk IV 70: Wilt thou cut Faces evermore, / For Husband dead as Nail and Door?
[UK]J. Ray Proverbs 202: As dead as a door nail.
[UK]Farquhar Constant Couple IV ii: He’s dead as a door-nail; for I gave him seven knocks on the head with a hammer.
[UK]J. Gay ‘A New Song of New Similes’ Poetical Works II (1854) 181: Soon as dead as a door-nail / Shall I be, if without her.
[UK]Laugh and Be Fat 144: Lo, here she lies without Bed or Blanket, / Dead as a Door-Nail. God be thanked.
[UK]Dying Groans of Sir John Barleycorn 4: In company with good wife’s member-mugs, where I must stand in the stink until starved as dead as a doornail.
[UK]Sporting Mag. July IV 234/1: But soon dead as a door nail / Shall I be without her.
[UK]C.M. Westmacott Eng. Spy I 245: I lie dead as a door-nail.
[UK]Mr Mathews’ Comic Annual 16: Och, he is as dead as a door nail.
[Ire] ‘A Letter [...] From Peter Strongbow etc.’ Dublin Comic Songster 310: Dead as a door nail, Paddy, my belly as full as salt wather.
[US]Bartlett Dict. Americanisms 109: dead as a door nail. Utterly, completely dead. The figure is that of a nail driven into wood, and, therefore, perfectly immovable; the word door is used for the sake of the alliteration. It is sometimes changed with us into the less appropriate phrase, ‘As dead as a hammer’.
[Aus]Bell’s Life in Sydney 3 Feb. 3/2: He knew his client, Mr. Kearney to be as dead a nail as himself.
[UK]G. Borrow Lavengro III 165: ‘Is she dead, then?’ ‘As a nail, brother.’.
[US]J.F. Brobst letter in Brobst Well Mary, Civil War Letters 45: That would have killed me dead as a doornail.
[US]Appleton’s Journal (N.Y.) 9 Dec. 669: There is another class of similes scarcely as pertinent; as, for instance: [...] talk to him like a Dutch uncle; smiling as a basket of chips; odd as Dick’s hatband; [...] sleep like a top; run like thunder; deader than a door-nail.
[UK]C. Hindley Life and Adventures of a Cheap Jack 23: He’s gone dead – dead as a coffin nail.
[UK]Hants. Teleg. 16 May 11/7: ‘Dead, hey?’ remarked Barnum. ‘As a coffin nail, sir,’ replied the keeper.
[SA]B. Mitford Fire Trumpet III 240: He’s dead as a doornail, bedad.
[US]C.F. Lummis New Mexico David 92: Both ’peared dead ’s nails.
[UK]F.W. Hume Hagar of the Pawn-Shop 68: ‘Dead!’ ‘As a doornail!’ replied the detective.
[UK]Boy’s Own Paper 8 June 564: Three male herons [...] had been picked up by the Squire’s keeper as dead as a door-nail.
[US]B.L. Bowen ‘Word-List From Western New York’ in DN III:vi 440: dead as a doornail, adj. phr. Entirely dead.
[US]J.E. Rendinell diary 17 July One Man’s War (1928) 143: We [...] took a crack at him finely brought the German down as dead as a doornail.
[UK]D.L. Sayers Unpleasantness at the Bellona Club (1977) 138: All those refrigerated old imbeciles [...] comin’ in and noddin’ to the old guv’nor like so many mandarins, when he was as dead as a doornail all the time.
[US]Ade Old-Time Saloon 1: The animal might be as dead as a door-nail.
[US](con. 1910s) J.T. Farrell Young Lonigan in Studs Lonigan (1936) 103: It’s dead as a doornail, you old sonofabitch.
[US]J.T. Farrell Gas-House McGinty 127: All the people [...] lie here, dead as a hangnail.
[US]E. Anderson Thieves Like Us (1999) 44: They were as dead as doornails.
[UK]D. Davin For the Rest of Our Lives 241: Dead as a doornail up in Syria. I’ve got my company and we just potter about trying to stop Jerry if he comes through Turkey.
[US](con. 1930s) H. Simmons Man Walking On Eggshells 92: That was the lick, the lick that laid poor Dick out deader than a doornail.
[US]Western Folklore XXV:3 195: As dead as a doornail.
[US](con. 1945) E. Thompson Tattoo (1977) 380: He was just a boy [...] and dead as a doornail.
[NZ]R. Morrieson Pallet on the Floor 74: Voot was as dead as a doornail.
[US]S. King Stand (1990) 1021: America is dead, dead as a doornail.
[Aus]A. Weller Day of the Dog 94: Poxy town is as dead as a doornail.
[UK]S. Grafton O is for Outlaw (2000) 369: You know, offed. Eliminated. Kilt him deader than a doornail.
[UK]Guardian Rev. 5 Feb. 2: ‘As bright as? cool as? dead as? ...’ [...] ‘a button’, ‘a cucumber’, ‘a doornail’.