Mongolian Tsa: The Dental Affricate

Tsa writes a dental affricate, the sound English spells ts, and it is the twenty-ninth letter of the alphabet and one of the ten added for foreign vocabulary. Unicode encodes it at U+183C. The sound is common in Chinese and in Tibetan and is not part of the native Mongolian consonant system, which has the palatal affricates but not the dental one. The letter is one of the clearest cases of an addition made for a specific body of loanwords, since almost every Mongolian word containing it can be traced to one of those two sources. Its shape is adapted from a letter already in the alphabet, following the script's usual practice.

Alphabet charts place it among the additions, after the inherited twenty-five, which is the arrangement that keeps the alphabet honest about what belongs to Mongolian and what has been supplied for other languages. For a reader the letter functions as a marker in the same way an initial trill or an initial voiceless bilabial stop does: it identifies the word as borrowed before anything else about it is known, and in a religious text it points first to Tibetan. Unlike the two native affricates it has no voiced partner in the alphabet, since the voiced sibilant that would pair with it was itself added separately and writes a fricative rather than an affricate.