Such letters are employed in spelling but are not pronounced, and English offers a wealth of examples more than any other language .

  • most final "b's" preceded by "m" (dumb, climb, thumb, etc)
  • most "k's" followed by "n" (knob, knight, knee, etc)
  • most "gh's" followed by "t" (night, thought, right, fight, etc)
  • most "l's" in "al" followed by "m" (calm, palm, almond - BrE, psalm, qualm, balm, alms, salmon, etc)
  • the "h" in certain words (hour, heir, honor, honest, ghost, exhausted, vehicle, etc)
  • etc.

Is there a phonetical term for them?

EDIT - The above examples have been given only for the sake of illustration. The question is about a phonetic term for silent letters.

  • 3
    Can you be more specific about the kind of term you want? You've already mentioned "silent letters"; this really seems the best and most straightforward option to me. I don't think it has anything to do with grammar, and the entire concept is not very well defined phonetically (there are unsolvable issues like "is the s or c silent in scent"; and "if the l in calm is silent, why isn't it pronounced the same way as cam?").
    – herisson
    Commented Jul 14, 2016 at 0:55
  • 7
    Yes, the term is "silent letter." "Ride" ends with a silent E. "Debt" contains a silent B. "Unknowable" contains two silent letters: K and E. Incidentally, the Ls in "calm," "palm," and "almond" are not silent. Anyway, sometimes silent letters are vestiges from another language or a prior pronunciation. Other times, since English doesn't use accent marks, silent letters are used as a tool to cue us how to pronounce an earlier sound.
    – user184292
    Commented Jul 14, 2016 at 1:22
  • 3
    @Centaurus Whether those Ls are silent depends on your accent. I certainly pronounce the L in almond and alms, if not the others, and ODO agrees. The silent P in ptermigan and pterodon might be less controversial.
    – choster
    Commented Jul 14, 2016 at 2:06
  • 1
    In the dialect of English I learned, in all of those "l" examples, the "l" is pronounced. Not the same as other "l"s, but it is an obvious sound before the "m" (tongue to the roof of the mouth, very briefly before going to the normal "m"). Of course, the dialect I learned growing up has several other silent letters you don't mention, like the silent "r" in "park".
    – MAP
    Commented Jul 14, 2016 at 2:54
  • 5
    There is no phonetic name for such letters. Letters are part of an orthographic system, while phonetics is part of speech, not orthography. English is still English when spoken, and not all its speakers can read or write it. Not to mention spell it. The fact that English has so many silent letters -- and so many different types of silent letters -- simply points out the fact that the English spelling system is terrible and doesn't represent the language well. But listing all the exceptions solves no problems and is depressing to boot. Commented Jul 16, 2016 at 14:40

7 Answers 7


Wikipedia references linguist Edward Carney's (Senior Lecturer in Phonetics at the University of Manchester) A Survey of English Spelling in this explanation on silent letters, so the names of these various terms are not standardized. He distinguishes between two types of 'silent letter': auxiliary and dummy:

  • Auxiliary letters, paired with another letter, constitute digraphs which represent a single distinct sound. These auxiliary letters are further classified into exocentric digraphs—where the collective sound of the digraph is different from the individual sound of each of its two letters. The individual letters are rarely considered silent because each letter contributes to the overall sound of the digraph. There are two categories of exocentric digraph:

    1. a phoneme with no single-letter representation, such as in consonants 〈ng〉 for /ŋ/ as in sing, 〈th〉 for /θ/ as in thin or /ð/ as in then, diphthongs 〈ou〉 in out or 〈oi〉 in point.
    2. a single-letter representation of a phoneme replaced with a digraph instead, such as 〈f〉 replaced by 〈gh〉 in enough or 〈ph〉 in physical

    —and endocentric digraphs, where the sound of the digraph is the same as that of one of its letters, which are classified into three groups:

    1. most double consonants, as 〈bb〉 in clubbed (but not geminate consonants, as 〈ss〉 in misspell because both s's contribute to the elongated /s/ phoneme)
    2. the discontiguous digraphs, whose second element is "magic e" (silent 〈e〉) , e.g. 〈a_e〉 in rate, 〈i_e〉 in fine
    3. others, such as 〈ck〉 (which is in effect the "doubled" form of 〈k〉); 〈gu〉 as in guard, vogue; 〈ea〉 as in bread, heavy, etc.

  • Dummy letters are letters that have no relation to neighboring letters and no correspondence in pronunciation, and are classified into two groups:
    1. inert letters, which are sounded in a cognate word: e.g. 〈n〉 in damn (〈n〉 is pronounced in damnation); 〈g〉 in phlegm (〈g〉 is pronounced phlegmatic); 〈a〉 in practically (〈a〉 is pronounced in practical)
    2. empty letters, which never have a sound, e.g. 〈w〉 in answer, 〈h〉 in Sarah, 〈s〉 in island, 〈b〉 in subtle, the 〈t〉 in ballet. These are the "truest" form of silent letter.

Other forms of silent letters:

  • consonant cluster silent letters: silent 〈th〉 in asthma

  • spurious silent letters: silent letters that are added to adopted words post factum to more accurately reflect even earlier origins, such as

    • silent 〈b〉 in debt and doubt (from French dette, doute) was inserted to match Latin cognates like debit and dubitable
    • silent 〈s〉 inserted in isle (Norman French ile, Old French isle, from Latin insula; cognate to isolate) and then extended to the unrelated word island.
    • 〈p〉 in ptarmigan was apparently suggested by Greek words such as pteron ('wing')
  • Non-rhotic 〈r〉 accents: 〈r〉 is silent in such words as hard, feathered

  • h-dropping accents: 〈h〉 is silent

  • silent letters in compound words: compound words are often simplified in pronunciation, while their spelling remains the same. For example, cupboard and breakfast were once pronounced as written, but were then simplified over time.

The Wikipedia section goes more in-depth on the purpose of silent letters and how they originate in words.

  • 1
    In my search for an answer I found the word “aphthong” ( thefreedictionary.com/Aphthong). At first glance it seemed to be exactly what I had been looking for. It’s a phonetical term and describes a silent letter in a word. A more careful analysis, however, showed that not all dictionaries list it. And maybe more important, it seems that nobody has ever heard it. Your answer looks perfect, thank you.
    – Centaurus
    Commented Jul 21, 2016 at 20:31

In phonetics, I find three terms used to designate a silent letter (or letters):

  1. 'silent letter',

  2. 'mute letter',

  3. 'zero sound', or simply 'zero'.

Of these, 'silent letter' (1) appears to be most common. The uses, however, might be said to be colloquial, rather than technical and specific to phonetics.

'Mute letter' (2) is also used. The term is attested in use with a special sense for grammar and phonetics, as shown in OED Online:

mute, adj. and n.
4. Grammar and Phonetics
b. Of a letter: not pronounced, silent.

["mute, adj. and n.3". OED Online. June 2016. Oxford University Press. http://www.oed.com/view/Entry/124309 (accessed July 18, 2016).]

Attestation ranges from 1638-2005. The publications cited are not, however, exclusively devoted to phonetics, but are more general: Barnabæ Itinerarium (1638); Hist. Druids (a1722); Proc. Philol. Soc. (1840); Dict. Mod. Eng. Usage (1926); Understanding French Verse (2005).

This sense of 'mute' is invariably adjectival.

Other—but obsolete, historical and rare—senses of 'mute' used as a noun and adjective in phonetics are given. These obsolete senses do not offer an answer to the question, because even if they were not obsolete, etc., they refer only to 'silent' consonants:

4. Grammar and Phonetics.
†a. Of a consonant: plosive, stopped. Obs.
†c. Of a consonant: voiceless. Obs.
B. n.3
1. Phonetics. A mute or stopped consonant; a plosive. Now hist. and rare.

(op. cit.)

'Zero sound' (3), also 'zero', however, promises to offer a complete and direct answer to the question. The term and the (absence of) sound it denotes is represented in IPA with ∅.

In an alphabetic writing system, a silent letter is a letter that, in a particular word, does not correspond to any sound in the word's pronunciation. Phonetic transcriptions that better depict pronunciation and which note changes due to grammar and proximity of other words require a symbol to show that the letter is mute. Handwritten notes use a circle with a line through it and the sound is called "zero"....

(Wikipedia, "Silent letter")

While I was at first incredulous (for philosophical reasons, among others), I quickly uncovered support, that is, attestation for the sense, in a wide range of publications specifically dealing with phonetics. I offer a somewhat random selection from those publications:

In accordance with the phonetic laws of the Türkic language the word aluank could have variants Alan, Alban, Alvan. The sound k, apparently, is a part of an affix of belonging -nyky (Aluinnyky - ‘the people belonging to aluan’). Strongly reduced y (like “i“ in “it“) is almost not heard, therefore it dropped out very quickly, double nn in due course gives one n, thus comes a word aluank, where the sound k is further reduced. As to the sound u, it sounds as w, and w usually sounds as a zero sound, or b, or v.

(From Alans - Türkic etymology; bold emphasis mine.)

If the sound that should cover the phonological /r/ slot is not present, tier 2 will simply indicate zero. The symbol adopted in the picture is [Ø].

(From "Diachronic change in the postvocalic /r/ in the Dutch of Amsterdam. Section 9.3.2. Zero sound and special cases", p. 29.)

This group can also yield j and zero sound, but these cases are very easy to explain and therefore will not be dealt with at length in this article.

(From note 1, p. 2, in "An Unknown Law of Elision in Western Romance Languages", Revista Eletrônica de Divulgação Científica em Língua Portuguesa, Lingüística e Literatura - Ano 04 n. 06-1º Semestre de 2007. See also two other instances in this article.)

... mainly to facilitate making the distinction between glottal stop and zero as in [a?e] versus [ae].

(From "Auditory vs. Articulatory Training in Exotic Sounds. Final Report", p 3.)

  • The phonetic sense of "mute" in which it refers to plosives or voiceless consonants does not refer to silent consonants. A plosive is a consonant like p t k b d g; a voiceless consonant is like p t k s f h. Using "mute" to mean "plosive" is old terminology taken from Latin; it refers to the impossibility of sustaining such sounds by themselves.
    – herisson
    Commented Jul 18, 2016 at 17:13
  • @sumelic, "does not refer to silent consonants": hence my scare quotes around 'silent' in that reference, but your failure to take the point is understandable, given that this is one of the few times I've overloaded the signification of single quotes (as opposed to the frequent overloading of italic signification found on this site).
    – JEL
    Commented Jul 18, 2016 at 17:44

A silent letter is called an aphthong.

/ˈafθɒŋ/ Etymology: modern < Greek ἄϕθογγος voiceless, ἄϕθογγον a consonant.

‘A letter which is not sounded in the pronunciation of a word; a mute.’ Craig 1847.

— OED, an entry not updated since 1885.

There is an earlier (not OED) reference for 1817 “An Irish English Dictionary” Edward O’Reilly Dublin PAGE 882

aphthong /af-thong/, n One or more letters that are customarily silent in the pronunciation of a word ….. Examples the first d in Wednesday /wenz-dee or wenz-day/, the p in psychology.

Recent appearances of "apthong" now are only found in lists of rare words.

  • 1
    This would benefit from the inclusion of an authoritative dictionary definition. Commented Jan 29, 2021 at 20:37
  • @KillingTime I think this will be difficult, if you google this word, the closest from an authoritative source that you will find is a user suggestion in Collins, and one entry in the Wiktionary.
    – Otter
    Commented Jan 29, 2021 at 21:42
  • @Otter OED: aphthong, n. Pronunciation:/ˈafθɒŋ/ Etymology: modern < Greek ἄϕθογγος voiceless, ἄϕθογγον a consonant. A letter which is not sounded in the pronunciation of a word; a mute.’ Craig 1847. Earlier (not OED) 1817 “An Irish English Dictionary” Edward O’Reilly Dublin PAGE 882 aphthong /af-thong/, n One or more letters that are customarily silent in the pronunciation of a word ….. Examples the first d in Wednesday /wenz-dee or wenz-day/, the p in psychology. [comment] Now only appearing in lists of rare words
    – Greybeard
    Commented Jan 29, 2021 at 22:05
  • 1
    @Greybeard you could edit the answer and insert this info, providing the source. If the edit is approved, you're going to earn a badge (idk which now)
    – Otter
    Commented Jan 29, 2021 at 22:19
  • 1
    Because if you refer to the edited version, I can't see how it does not provide an answer for the question. In fact, it's a precise answer to the question: a phonetic term the designates a silent letter in a word. It is archaic, unknown and probably useless, but still a specific and exact answer.
    – Otter
    Commented Jan 30, 2021 at 13:43

I was taught that the term for a word, or more properly the letter in a word which is not pronounced is Asonant. e.g. Aisle

  • Welcome to ELU. That’s a good answer and IMO it might be better than the accepted answers. Could you add a definition (text and link as links can decay) to make it a great answer?
    – Pam
    Commented Jun 10, 2018 at 8:54
  • Any references to bear you out ? MW and ODO have a different definition for "asonant".
    – Centaurus
    Commented Jun 18, 2018 at 13:39
  • Another term I’ve seen is asonant which means not sounding, versus sonant which means a voiced syllable capable of forming a syllable (from Wiktionary.com). Commented Nov 11, 2023 at 19:54

Sumelic, FWIW, if you don't pronounce the "l" in "calm", it's pronounced almost like "com" (as in website.com), not "cam" (as in a component in some machinery). Similarly with "palm" without the /l/ sound: pahm or pomme, not pam (short for Pamela). My accent includes the /l/, but not very strongly: I don't pronounce "calm" the same as "column". Although the p in "ptarmigan" is etymologically unwarranted, I generally put a faint--almost inaudible--trace of a /p/ before the t on those rare occasions when I have to pronounce the word; and I similarly put a trace of a /p/ before the t or s in "pterodactyl" and "psychology" and similar words. An affectation on my part, perhaps.

I had never come across "aphthong". I like the word. The comments above on auxiliary and dummy letters are enlightening.

  • Mention that you read "aphthong" in a comment by the OP and add the dictionary link, and it's +1 from me. en.wiktionary.org/wiki/aphthong
    – Mari-Lou A
    Commented Jun 10, 2018 at 7:26
  • calm, palm etc. can have an audible "L" sound depending on the region
    – wrymug
    Commented Jun 21, 2018 at 23:39

Variant: Elide

It depends on whether the letter is intended to be silent. The current answers all imply the silence was expected, e.g. the 's' in Aisle or Island, and I do not want to cover the same ground. There is another word to describe when a letter is not pronounced when it 'should' be and that is 'Elide'. The example I would give is from a recent phrase, "No you Di''t" My apologies for the representation as I'm not sure how to express the missing sound other than to include a single quote like with a contraction. Another place I've heard the same behavior is with a word with an internal 'T' sound that also ends with a hard 'T', e.g. "Im-por-tant" becomes "Im-por'-ant"; the inner 't' has been elided.

I want to give this site credit but I can't seem to find the post from which I learned the term and searching gives way too many results. You are welcome to edit other references but know I discovered the term here.


The word you are looking for is aphthong. Humans are lazy and started saying "silent letter" in lieu of using the correct terminology, and the word has been all but forgotten.

  • 3
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