diphthong

/ˈdɪfˌθɒŋ(ɡ)/

//ˈdɪfˌθɒŋ(ɡ)// noun

By · According to Wiktionary data (CC BY-SA) ·

"diphthong" is a 9-letter English headword indexed on PlainSpell.

The verdict

“diphthong” is uncommon English (frequency #85,178 among 3,470 “D” headwords), classed as a noun. The kind of spelling people second-guess.

#85,178
frequency rank, English
3,470
“D” headwords

According to Wiktionary data (CC BY-SA, analyzed September 3, 2026) - A complex vowel sound that begins with the sound of one vowel and ends with the sound of another vowel, in the same syllable.

Corpus desk

Index EN-diphthong · diphthong · English

diphthong · rank #85,178 · 0 variants · 0 confusables

  • FREQ-RARE #85,178
  • LEN-LONG 9 letters
  • VOW-2 2 vowels
  • CONFUS-0 No pairs
  • VAR-0 0 variants
  • BOOK-MID 3,470
  • PHOTO-FINISH diluent

Nearest frequency peer: diluent (-2 rank slots)

Read with this headword: Spelling guide for this pattern

Desk codes from Wiktionary headword shape, FrequencyWords rank tier, confusable-pair count, generated misspelling depth, letter-cohort book size, and photo-finish peer. Not a difficulty grade.

Long-tail ranks near “diphthong”

Sparse band: bars invert rank so rarer forms read shorter

corpus weight

What this shows Long-tail view: where “diphthong” sits against similarly uncommon English ranks.

Source FrequencyWords open word-frequency list As of September 3, 2026
Key facts for diphthong
PropertyValue
Headworddiphthong
LanguageEnglish
Part of speechNoun
IPA/ˈdɪfˌθɒŋ(ɡ)/
Letters9
Frequency rank#85,178
Misspellings tracked0
Confusable pairs0
SourceWiktionary (kaikki.org)

Long-tail rank of “diphthong” in English

This scale runs from the tiny cluster of words that carry ordinary speech (left) to the long tail of words almost nobody reaches for (right).diphthongfalls in this rarity band:

#1#100#1K#10K#100K
← used constantlyrarely used →

The axis is logarithmic, with each marked tick roughly ten times rarer than the last. Rare peers in the same band: “diluent” (#85,176), “discontinuance” (#85,180), “dihedral” (#85,175). Among 3,470 “D” headwords, “diphthong” is #85,178. Source: FrequencyWords open word-frequency list.

Rare enough to double-check

diphthong is uncommon English at frequency #85,178 among 3,470 “D” headwords, classed as anoun, transcribed /ˈdɪfˌθɒŋ(ɡ)/. Rarity is why readers land here mid-draft. 3 senses are on record.

We couldn't generate a plausible misspelling set for diphthong, typically a sign the spelling maps closely to how the word sounds. This entry stands alone in our confusable dataset, suggesting its spelling stands apart enough that readers rarely confuse it with something else.

Etymologically, the entry records: PIE word *dwóh₁ From French diphtongue, from Late Latin diphthongus, from Ancient Greek δίφθογγος (díphthongos, “two sounds”), from δίς (dís, “twice”) + φθόγγος (phthóngos, “sound”). The correct English form is diphthong, spelled D-I-P-H-T-H-O-N-G.

Definition

  1. 1
    A complex vowel sound that begins with the sound of one vowel and ends with the sound of another vowel, in the same syllable.
  2. 2
    A diaphoneme realized as a two-target vowel in some but not necessarily all dialects.
  3. 3
    A vowel digraph or ligature.

Recorded use

Wiktionary examples

These source excerpts show how diphthong appears in context. They illustrate usage; the definition above remains the entry’s reference meaning.

  1. In Lang Belta vowels usually appear preceding or following a consonant (see previous examples), and as of now no occurrence of diphthongs or triphthongs has been attested.
  2. And he might have written the name, also, with the diphthong æ, as well as the single vowel, in the initial syllable, throughout all the preceding forms.

Etymology

PIE word *dwóh₁ From French diphtongue, from Late Latin diphthongus, from Ancient Greek δίφθογγος (díphthongos, “two sounds”), from δίς (dís, “twice”) + φθόγγος (phthóngos, “sound”).

This word in other languages

diptongo(Español)diphtongue(Français)Diphthong(Deutsch)

Definitions, pronunciation, and etymology for this entry are drawn from Wiktionary via the kaikki.org structured extract (CC BY-SA); frequency ordering uses the FrequencyWords open word-frequency list (2018 English corpus, MIT). See the methodology for how each field is sourced and updated.

Frequently Asked Questions

How do you spell "diphthong"?
"diphthong" is spelled D-I-P-H-T-H-O-N-G. The IPA pronunciation is /ˈdɪfˌθɒŋ(ɡ)/.
What does "diphthong" mean?
As a noun, "diphthong" means: A complex vowel sound that begins with the sound of one vowel and ends with the sound of another vowel, in the same syllable.
How do you pronounce "diphthong"?
The IPA (International Phonetic Alphabet) transcription for "diphthong" is /ˈdɪfˌθɒŋ(ɡ)/. Click the speaker icon on the pronunciation badge above to hear it spoken aloud where audio is available.
What is the origin of the word "diphthong"?
PIE word *dwóh₁ From French diphtongue, from Late Latin diphthongus, from Ancient Greek δίφθογγος (díphthongos, “two sounds”), from δίς (dís, “twice”) + φθόγγος (phthóngos, “sound”). See the full etymology section above for more details.
Is PlainSpell free to use?
Yes, PlainSpell is a completely free word reference. You can look up definitions, pronunciations, confusable pairs, homophones, and spelling corrections across 5 languages without any sign-up or subscription.

Similar English words by spelling shape

Same letter count and similar misspelling depth for "diphthong", not the corpus desk frequency band.

Same letter count

Frequency-ranked English headwords with 9 letters (nearest by frequency rank).

derringer#85,167downtempo#85,193decennial#85,158dubiously#85,199

Source: Wiktionary (via kaikki.org) Structured Wiktionary extract

Source: FrequencyWords open word-frequency list