Mongolian Ra: The Trill That Begins No Native Word

Ra writes the trilled or tapped r and is the twenty-third letter of the alphabet. Like the velar nasal, it carries a restriction rather than an alternation: no native Mongolian word begins with it, so a word starting with r is a borrowing. The restriction is shared with Turkic languages and is one of the features often cited in discussions of what the languages of the region have in common.

Unicode encodes ra at U+1837. Inside and at the end of words the sound is entirely ordinary and common, so the constraint is narrowly about the initial position rather than about the sound at large. For a reader the letter is a useful signal. An initial r on a Mongolian page points to Tibetan, Sanskrit, Chinese or Russian vocabulary, and in a Buddhist text it points to the first of those two. Speakers of languages with this restriction commonly deal with borrowed words by adding a vowel in front of the r or by altering the consonant, and older layers of loanwords in Mongolian show such adjustments while newer ones increasingly do not, which is one of the ways a borrowing can be dated roughly by its shape. The letter itself is plainly written and carries no harmony alternation and no shared shape, so it is one of the shapes a reader identifies without effort. What it demands is knowledge of the lexicon rather than of the script: the letter is easy, and the inference a reader draws from finding it at the head of a word is where the real information lies.