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|Sound change and alternation|
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.