Monophthongs

Monophthongs are vowel sounds characterized by a relatively stable articulatory configuration during their articulation, i.e., their quality does not change much throughout the vowel's duration. They are contrasted with diphthongs, which involve a perceptible transition between two distinct vowel qualities within the same syllable.

In phonemic inventories, monophthongs are typically described by their height (high, mid, low), backness (front, central, back), and lip rounding (rounded vs unrounded). They can be short or long depending on the language. The exact inventory and the way vowels interact with stress, syllable structure, and phonotactics vary across languages.

Many languages rely primarily on monophthongs as the nucleus of syllables, with a set of distinct vowels that do not require a glide to be pronounced. For instance, Spanish has five primary monophthongs: [i], [e], [a], [o], [u], while French and German have larger sets that include mid and high vowels. English contains both monophthongs and diphthongs, and some vowels that are diphthongal in other dialects may be realized as monophthongs in particular varieties.

Prototypical transcription uses a single IPA symbol to denote each monophthong, e.g., [i], [e], [a], [o], [u], with additional symbols for more varied inventories. The presence and prominence of monophthongs are influenced by historical changes, language contact, and dialectal variation. In some languages, monophthongization has reduced diphthongal contrasts, while others maintain a robust system of both monophthongs and diphthongs.