monophthong

IPA/ˈmɒnəfθɒŋ/
IPA/ˈmɑːnəfθɔːŋ/

monophthong — noun

  • monophthongsingular
  • monophthongsplural

1. a single, pure vowel where the speaker holds the mouth and tongue in one fixed s

1.nounC2
Definition

a single, pure vowel where the speaker holds the mouth and tongue in one fixed shape from start to finish — for example, the long /iː/ in 'see' — unlike a diphthong, which glides from one vowel to another inside the same syllable.

Example

Adina's teacher explained that the /iː/ in 'see' is a monophthong.

frame: the X sound in [word] is a monophthong

In parts of northern England, the vowel in 'goat' is pronounced as a clear monophthong.

regional accent context

Common collocations
  • pure monophthong
  • long monophthong
  • short monophthong
  • produce a monophthong
  • monophthong vs diphthong
Synonyms
  • pure vowel

    everyday-prose equivalent; preferred outside academic writing

  • simple vowel

    informal teaching term, common in classroom contexts

Antonyms
  • diphthong

    a vowel that slides from one quality to another within a single syllable

  • triphthong

    a vowel that moves through three qualities, e.g. the sound in 'hour'

Usage Note

Almost exclusively used in linguistics, phonetics teaching, and accent coaching; the everyday equivalent would be 'pure vowel'. Often appears in contrast with 'diphthong' (a vowel that glides between two qualities) — readers usually meet the two terms together.

Common Mistakes

The word "boy" ends in a monophthong.
The word "boy" ends in a diphthong.
the vowel in 'boy' glides from /ɔ/ to /ɪ/, so it is a diphthong, not a monophthong.
Mono-thong
monophthong' (pronounced /ˈmɒnəfθɒŋ/)
note the silent 'ph' before the 'th'; many learners drop the /f/ sound or break the word in the wrong place.

Word family

  • monophthongal
    adjectiveC2
  • monophthongize
    verbC2
  • monophthongization
    nounC2
  • diphthong
    nounC1

Synonym discussion

Sense: noun/1

In phonetics, 'monophthong' is the technical label for a vowel produced with one steady tongue and lip position — its everyday paraphrase is 'pure vowel', which teachers often use with beginners because the Greek-rooted term feels intimidating. 'Diphthong' is the direct contrast: a single syllable whose vowel quality glides from one position to another, such as the sound in 'boy' or 'how'. The umbrella word 'vowel' covers both monophthongs and diphthongs (and the rarer triphthongs), so it is too broad when you need to specify the type. Choose 'monophthong' in academic writing, accent training, or language teaching where precision matters; choose 'pure vowel' when speaking to a general audience.

monophthong ↗pure voweldiphthongvowel ↗

Common collocations

Nouns

  • monophthong inventory
  • monophthong symbol
  • monophthong system

Phrases

  • pure monophthong
  • long monophthong
  • short monophthong
  • monophthong vs diphthong

Prepositions

  • the monophthong in [word]
  • monophthong of [language / dialect]

Etymology

GreekLatinEnglish

From Greek 'monos' meaning 'single' or 'alone' + 'phthongos' meaning 'sound' or 'voice'. The compound entered late-nineteenth-century linguistics scholarship as a tidy counterpart to the older term 'diphthong' (Greek 'di-' = two), which English had borrowed from Latin in the late Middle Ages.