Silent and invisible letters in English

Silent letters constitute a notorious phenomenon in English: in wréstle, for example, only four out of the seven letters are actually sounded (*résl), and there can be strings of them in place names, exemplified by the trio Léicester, Glóucester and Worcester, pronounced Léster, *Glóster and *Wùster. (The accents show stress and pronunciation, see English spellings; * is placed before an incorrect spelling.)

Silent letters can be misleading, as in Thaîland and îsland, which rhyme, or they can be easy to ignore ("redundant"), as in wróng, yeôman, and lôw.

They can serve to distinguish between words that sound the same:

knôw knowledge = nô ''negative

knót tie = nót ''negative

wráp parcel = ráp ''knock, talk

wrîte read = rîght correct = rîte ''ritual

chéck verify = BrE chéque ''money

Some typical examples

 * b finally after m or before final t (-mb -bt)
 * g or k initially before n (gn-, kn-)
 * gh finally or before final t (-gh -ght)
 * l after à and before final f or m (-lf -lm)
 * n finally after m (-mn).

Alphabetical list
Silent A is found in: hëard, lëarn,  Múrray = Mòray;  all examples from Latin of aê: nébulaê, fŏrmulaê, and in the standard British English pronunciation of words ending in -ary: sécondary, díctionary

B: thúmb, dúmb,  númb,  clîmb,  límb,  débt,  dòubt,  súb'''tle

C: indîct, Tûcsón,  Connécticut,  blancmànge (*bləmónzh); sometimes there is a redundant soft c after s before a front vowel: scêne,  scîence,  effervésc'''e

CH: yàcht (*yót)

D before a soft g: dódge,  édgy,  lódging,  bádger,  brídge,  wédge; for most speakers in  Wédnesday; and before a French j in  Djiboûti,  Abid'''jàn

E: very commonly as final mute e, usually lengthening the preceding vowel, as in lâte, kîte,  hôpe,  Jûne; in the regular past tense ending, as in loòked, lëarned; exemplifying both of these uses, as in hoped, wâned; in heàrt,  heàrth; redundant in yeôman; and in síngeing (*sínjing, from sínge, to distinguish it from sínging, from síng)

F: hâlfpenny (*hâypəny)

G: before n: sîgn, desîgn, dèign,  rèign monarch (= rain weather), campâign, fóreign (BrE *fórən, AmE *fŏrən), sóvereign (BrE *sóvrin, AmE *sàvrən); gnásh, gnåw, gnôme, gnát, gnàrled,  Colôgne and in phlég'''m

GH: sîgh, rîght,  fíght,  fríght, night,  fŏught,  ŏught,  cåught,  èight,  wèigh'''t

H: hônour, hónest,  héir,  hòur,  vêhicle,  àùtobàhn, ôh, ôhm, Jóhn (cf. Jôan),  Thaîland,  Délhi, ghôst,  ghàstly, in the BrE  name-suffix -ham: Béckenham, Chéltenham, Twíckenham, and almost always after a consonant: see H for an alphabetical list of two-letter combinations from àh to '''zh

I:	after u: sûit, recrûit,  frûit,  jûice,  sluîce,  brûise,  crûise;  in cárriage and márriage; in several unstressed -ain and -eign endings: cërtain (*sërtən), cürtain (*kërtən), Brítain (*Bríttən), fóreign (BrE *fórən, AmE *fŏrən), sóvereign (BrE *sóvrin, AmE *sàvrən); in pláid (optionally), pláit, friénd,  pàrliament, business (*bíznəs), Sioux (*Soô), Sålisbury (*Sålzbəri) J is often silent in marijuàna and AmE Juàn

K, initially, before n: knôw, knêe,  knîght,  knít,  knâve,  knóll,  knót,  knîfe,  knêad massage; redundant after c, as in  báck

L: before d: coùld (*koòd, *kəd), woùld (= woòd tree, *wəd), shoùld (*shoòd, *shəd); before m: càlm, bàlm,  psàlm, sálmon, Málcolm (*Málkəm); before f: càlf, hàlf,  hâlfpenny; before v: càlve, hàlve; before k: fôlk,  tålk,  wålk,  and in Líncol'''n

M: m'''nemónic

N: after m: cólumn (and optionally cólumnist), condémn,  hýmn,  åutumn,  dámn,  sólemn

NC: blancmange (*bləmónzh)

O: after e: pêople, léopard,  jéopardy,  Géoffrey  (= Jéffrey) and all BrE examples from Latin of oê: phoênix, oênólogy, foêtus (where AmE omits the o); optionally in the BrE unstressed ending -borough (-brə or -bərə): Mårlborough (*Målbrə, *Målbərə), Scàrborough (*Scàbrə, *Scàbərə); and in chócolate (*chóclət) and èyot islet (= èight 8)

P: before t: recêipt, ptàrmigan, pterodáctyl; before n: pneumátic, pneumônia; before s: psàlm, p'''seûd

Q: Colquhoûn (*Cohoôn)

R: Standard British English, that is, most of England, and also in some areas in the US (in Scotland and most of the US, r is always pronounced)—a small selection: îron,  àrm,  àrt,  céntre,  mürder,  pãir,  mŏre,  dŏor,  desîre,  squãre, 	hîre,  përson,  Thürsday; also in a few French borrowings like bùstièr (AmE *bûstiây, BrE *bústiay)

RPS:	cŏrps (r sounded in AmE)

S: chássis, prècis,  Àrkansås,  Íllinois, Des Mŏines (*Dimŏyn), Loûisville (*Loôivíl),  îsland,  îsle = aîsle, rendezvous (*róndâyvoô)

T: after s: lísten, whístle,  wréstle,  càstle,  mústn’t;  bùffèt,  óften,  mŏrtgage,  bìdèt,  Màrgot,  wåltz (*wålss),  bôatswain, (can be written bôsun),  Tchaikóvsky, tsunàmi, and before ch in words such as ítch, cát'''ch

U: bìscuit, cïrcuit,  buíld,  buŏyant,  guíld,  guílt,  guîde,  guàrd,  guéss,  guést, 	āu'''nt

UE: tòngue, burlésque,  grotésque,  vâgue,  rôgue,  barôque,  unìque,  plâgue; BrE only: cátalógue, dîalógue (-lóg in AmE)

V is silent in Leveson-Gǒwer (pronounced *Loôson-Gǒre) and in many English-speakers' pronunciation of the Russian name Vsévolod; traditionally it was also silent in Dáventry, pronounced *Dâintry, but this name is now usually pronounced as spelt

W:	two 2 (= to preposition = toô many, also), who (*hû),  whôle entire (= hôle space),  swŏrd,  ànswer,  wrîte paper,  wróng,  wréstle,  awrŷ,  åwful,  bôatswain (can be written bôsun), and before a consonant in the next word: knòw, nòw, yew tree (= yoû me); often in the BrE name-suffix -wích: Nórwich (*Nórrich, *Nórrij), Gréenwich (*Grénnich, *Grénnij, *Grínnij) and Hárwich (*Hárrich, *Hàrrij)—though w is pronounced and ch is always itself in Ípswich; often in the BrE name-suffix -wíck: Bérwick (*Bérrik), Ẁarwick (*Wórrik), Késwick (*Kézzik), Chíswick (*Chízzik)

X: faux-pàs (*fô-pà), Sioux (*Soô) and French plurals of -au words: cháteaux (*shátô), tábleaux (táblô)

Y: Îslay (*Îlə), Pêpys (= pêeps), Sándys  (= Sánds = sánds)

Z: lâissèz-fãire, rendezvous (*róndâyvoô)

Invisible letters
A much rarer phenomenon in English is the invisible letter, the opposite of a silent one, a letter which is pronounced but not written.
 * There is an invisible initial w in òne, which has the same pronunciation as the past tense of the verb to wín: òne 1 = wòn win.
 * In British English and Commonwealth English, there is a frequently sounded r between two words, the first of which ends in a vowel sound, and the second of which begins with one. In Mr Zénda ís hêre to sêe yoû, many speakers will pronounce an unwritten r between the final a of Zénda and the following word ís, as if Zénda were spelt "Zender" (which in a non-rhotic variant such as BrE would sound the same). Unlike the first example, this is not a compulsory usage, and the invisible r may be replaced by a glottal stop, or the first word may glide into the second with no r sound—in rapid, informal speech, of course, one would say: Mr Zénda's...
 * The Scottish word búrgh can be pronounced as the equivalent bòrough is in England, *búrə.
 * There is an invisible á following the M in names like McEnroe and McIlroy, which both begin Máck-: in some versions, and in other such names, the á is of course visible: MácKintosh person = máckintosh raincoat, as it is in Mackénzie, MacKénzie; and it really is unnecessary in the likes of McCǒrmack *Məcǒrməck.
 * A variant pronunciation of St Jóhn *Səntjón is *Sínjən, with an invisible í.
 * In slow speech, in Northámpton and Southámpton, an aspirate h may be heard in addition to the h of th.
 * Singular possessive forms that end in s' may have an extra s pronounced, as if ending in s's (also a correct form, and preferred by many): Dâvis' = Dâvis's (instead of = Dâvis).

Inversion
Another related phenomenon is pronunciation of letters in a different order from the written one.
 * In Scotland, North America, etc., wh is pronounced "hw" (this phoneme has also been analysed as an unvoiced w).
 * Many speakers pronounce nûclêar as *nûcular (though this is regarded as incorrect).