Phonemic merger

A sound change in which two previously distinct phonemes become indistinguishable in a language, removing a contrast that once distinguished words.

Phoneme: A speech sound category that distinguishes words in a particular language. A merger changes the inventory of these contrastive sound categories.
Cot–caught merger: The merger of the vowels in words such as “cot” and “caught” in many North American English varieties. It is a prominent ongoing regional merger in English.
Dialectology: The study of regional and social variation in language. Merger patterns distinguish dialects even when speakers share most of their vocabulary.
Apparent-time study: A method for inferring language change by comparing speakers of different ages at one time. Age patterns can reveal whether a merger is advancing or retreating.
Phonological change: A change over time in a language’s sound system or patterns. A merger is one outcome of sound-system change.
Wine–whine merger: The loss of the distinction between the initial consonants of “wine” and “whine” in many English varieties. It illustrates the merger of two historically distinct consonants.
Historical linguistics: The study of how languages change and develop over time. Merged contrasts help reconstruct earlier sound systems and language relationships.
Real-time study: A study that compares language use across observations made at different times. Repeated observations can confirm whether apparent-time merger patterns reflect historical change.
Neutralization: The loss of a phonological contrast in a particular environment. A merger removes a contrast throughout a language variety, while neutralization can be environment-specific.
Mary–marry–merry merger: The pronunciation of the vowels in “Mary,” “marry,” and “merry” as the same in some English dialects. It shows how multiple vowel contrasts can collapse into one.

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