Th (digraph)

In linguistics, the digraph "th" represents a sound that can be either a voiceless dental fricative (IPA: θ) as in the English word "thin", or a voiced dental fricative (IPA: ð) as in the English word "this". The distinction between these two sounds is crucial for distinguishing many words in English.

The representation of these sounds by the digraph "th" is a historical convention. In Old English, the runes þorn (þ) and eð (ð) were used for these sounds. Over time, the scribal practice of using "th" to represent these sounds became more common, eventually replacing the runes.

The "th" digraph can present challenges for learners of English, as other languages may not have equivalent sounds. Some languages may approximate the sounds with a /t/ or /d/ sound, or a cluster like /s/ or /z/ followed by /t/ or /d/.

The pronunciation of "th" can also vary depending on dialect and specific words. For example, in some dialects, "clothes" may be pronounced with a /z/ sound instead of a /ð/. Some loanwords into English retain different pronunciations of "th" based on their original language. For example, in some pronunciations of "asthma," the "th" is silent.