Monophthongization

Sound change and alternation
Metathesis Quantitative metathesis
Lenition Consonant gradation Consonant voicing and devoicing Assibilation Spirantization L-vocalization Debuccalization
Fortition
Epenthesis Prothesis Paragoge Unpacking Vowel breaking
Elision Apheresis Syncope Apocope Haplology Cluster reduction
Transphonologization Compensatory lengthening Nasalization Tonogenesis Floating tone
Assimilation Fusion Coarticulation Palatalization Velarization Labialization Final devoicing Metaphony (vowel harmony, umlaut) Consonant harmony
Dissimilation
Sandhi Liaison, linking R Consonant mutation Tone sandhi Vowel hiatus Synalepha Elision Crasis Synaeresis and diaeresis Synizesis
Other types Apophony Affrication Gemination Clipping Fronting Raising Betacism Iotacism Fusion Merger Compensatory lengthening Monophthongization Rhotacism Rhinoglottophilia Sulcalization Shm-reduplication Consonant mutation Vowel shift Chain shift

Monophthongization is a sound change by which a diphthong becomes a monophthong, a type of vowel shift. It is also known as ungliding, as diphthongs are also known as gliding vowels. In languages that have undergone monophthongization, digraphs that formerly represented diphthongs now represent monophthongs. The opposite of monophthongization is vowel breaking.