Devanagari Ssa ष

Ssa is the thirty-first consonant of the varnamala, the retroflex sibilant and the second of the three, made with the tongue tip curled back towards the roof of the mouth. In classical Sanskrit it arises very largely by rule: a dental sibilant is converted into it in the neighbourhood of certain preceding sounds, in the same way and under related conditions to those by which the dental nasal becomes retroflex. A written text therefore shows it at places where a rule has operated, and reading it back to the underlying dental is part of the analysis a student of the grammar performs.

In modern speech across much of northern India it has merged with the palatal sibilant, so the letter marks a distinction that many present-day readers of the script do not make aloud. It is also one of the two elements of a famous conjunct, joining the first consonant of the varnamala to form a compound sign so distinctive that many schoolbooks teach it at the end of the alphabet chart as though it were a letter in its own right. It is not one; it is a cluster, and the varnamala proper has thirty-three consonants. Because most of its occurrences are derived rather than inherited, the letter is a useful diagnostic when reading. Meeting it usually means that the underlying form carried a dental sibilant and that a rule has applied, and a reader working out the constituents of a long compound can use it as evidence about where the internal boundaries of that compound fall.

Devanagari primers commonly finish the alphabet chart with two or three conjuncts, most often the cluster of the first consonant with this sibilant, the cluster of the dental stop with the semivowel ra, and the cluster of the palatal nasal with the voiced palatal that opens the word for knowledge. They are printed in the same grid as the letters and learned in the same recitation, and a great many learners consequently believe the alphabet has a few more members than it does. It does not.

The varnamala has fourteen independent vowels and thirty-three consonants, and these three are compound signs built from letters already in the table. They are taught because they are frequent, because their written forms are far enough from their components to need separate learning, and because the last of them is pronounced so differently across the subcontinent that a learner benefits from meeting it explicitly. This atlas seeds the forty-seven letters and not the conjuncts, on the ground that a conjunct is a way of writing a sequence rather than a member of the series. That is a decision about scope and it is recorded here so that a reader who counts the entries and expects fifty knows why the count comes out where it does.