Devanagari Aa आ

Sanskrit measures vowels by duration, and the pairing of a short vowel with its long counterpart is the organising principle behind the opening of the varnamala. A short vowel occupies one mora, a matra in the metrical sense of the word, and a long vowel two; the difference is not stylistic but changes what a word means and what grammatical form it is, so the script needed a way to record it and the vowel signs supply one. Long aa is written after a consonant as a single upright stroke placed to the right of the letter, one of the simplest of the matra signs and the one a learner meets first, since it is also the sign that shows the inherent short a has been replaced rather than merely present.

The independent letter shown here is used only where the vowel opens a word or follows another vowel. Its form is the short letter with the same upright stroke added, a visual logic the script applies consistently: the long member of a vowel pair is usually the short member modified rather than an unrelated shape. Articulation is identical to short a in place, formed in the throat with the tract open, and differs only in the time it is held, which is why the phoneticians treat the two as one vowel quality in two quantities rather than as two sounds. Behind the Devanagari shapes lies a Brahmi ancestor, and Richard Salomon's survey of Indian epigraphy traces the descent of these forms through the inscriptional hands of the intervening centuries.

Long aa does more grammatical work in Sanskrit than any other vowel. It forms the commonest class of feminine noun stems, so a large proportion of goddess names and of abstract nouns in the tradition end in it. It marks several case endings, including the plural of the neuter and the instrumental singular of a major stem class. It serves as a verbal prefix meaning towards or up to, reversing the direction of the verb it attaches to, and it is the vowel that results when certain pairs of vowels meet at a word join under the rules of sandhi, the euphonic combination that Sanskrit applies across word boundaries as well as inside words. Because sandhi is applied in writing as well as in speech, a recited or manuscript text is full of long aa in places where the underlying words carried short vowels, and reading such a text back into its constituent words is a skill taught alongside the letters themselves. In recitation the length is audible and is trained deliberately, since the metres of the Vedic hymns and of classical verse are quantitative, built from patterns of light and heavy syllables rather than from stress. A misjudged vowel length breaks the metre, which is one reason the oral transmission of these texts developed such elaborate techniques of checking.

Within the Tantric reading of the alphabet as a garland of letters, the short and long vowels together make up the class the schools call the seed sounds or the vowels proper, distinguished from the consonants that follow them; the arrangements differ from school to school and are described in the scholarly literature rather than settled by it.