The most logical use of ⟨th⟩ is to represent a consonant cluster of the phonemes /t/ and /h/, as in English knighthood. … See more

The digraph ⟨th⟩ was first introduced in Latin to transliterate the letter theta ⟨Θ, θ⟩ in loans from Greek. Theta was pronounced as an aspirated stop /tʰ/ in Classical and early Koine Greek.
⟨th⟩ is use… See more

During late antiquity, the Greek phoneme represented by the letter ⟨θ⟩ mutated from an aspirated stop /tʰ/ to a dental fricative /θ/. This mutation affected the pronunciation of ⟨th⟩, which began to be used to represent the phone… See more

English also uses ⟨th⟩ to represent the voiced dental fricative /ð/, as in father. This unusual extension of the digraph to represent a voiced sound is caused by the fact that, in Old English, the sounds /θ/ and /ð/ stood in … See more

In the Latin alphabet for the Javanese language, ⟨th⟩ is used to transcribe the phoneme voiceless retroflex stop ʈ, which is written as ꦛ in the native Javanese script. See more

Because neither /tʰ/ nor /θ/ were native phonemes in Latin, the Greek sound represented by ⟨th⟩ came to be pronounced /t/. The spelling retained the digraph for etymological reasons. This practice was then borro… See more

In the transcription of Australian Aboriginal languages ⟨th⟩ represents a dental stop, /t̪/. See more