Th-stopping

Th-stopping is the realization of the dental fricatives [θ, ð] as stops—either dental or alveolar—which occurs in several dialects of English. In some accents, such as some varieties of Irish English, Newfoundland English, New York City English, and Indian English, they are realized as the dental stops [t̪, d̪] and as such do not merge with the alveolar stops /t, d/. Thus pairs like tin/thin and den/then are not homophonous. In other accents, such as Caribbean English, Nigerian English, and Liberian English, such pairs are indeed merged.Th-stopping occurred in all continental Germanic languages, resulting in cognates such as German die, "the", and Bruder, "brother".

New York City English

For some New Yorkers, the fricatives /θ/ and /ð/ are pronounced as affricatives or stops, rather than as fricatives. Usually they remain dental, so that the oppositions /t-θ/ and [d-ð] are not lost. Thus thanks may be pronounced [θæŋks], [tθæŋks], or [t̪æŋks] in decreasing order of occurrence; all are distinct from tanks. The [t̪] variant has a weakish articulation. The /t-θ/ opposition may be lost, exceptionally in the environment of a following /r/ (making three homophonous with tree), and in the case of the word with, (so that with a may rhyme with the non-rhotic pronunciation of "bitter-bidder"; with you may be [wɪtʃu], following the same yod-coalescence rule as hit you. These pronunciations are all stigmatized.