Kha, the Word for Empty Space, and Its Use for Zero

Alongside the letter there is a Sanskrit word kha, meaning a hollow, an aperture or the space of the sky, and that word has a second life in the technical vocabulary of Indian mathematics, where it is among the terms used for zero. Indian mathematical writing of the classical period was largely in verse, and its authors drew on a stock of synonyms so that a number could be expressed in whatever word the metre would take; the words chosen for zero are words for emptiness, sky and void, and kha is one of them. The practice is well documented in the histories of Indian mathematics and is a good illustration of how technical and poetic language ran together in that tradition. As with ka, this atlas records the word and keeps it distinct from the letter.

A Devanagari letter is named by the sound it makes, so any Sanskrit word of one syllable will share its name with a letter, and the coincidence carries no implication about the sign. What can be said about the letter kha itself is what the phonetic table says: it is velar, voiceless, aspirated, and second in the first class, and its written form descends through the Nagari hands from a Brahmi letter of the same value. The number of things that can truthfully be said about an individual consonant of a phonetically ordered alphabet is smaller than the number that can be said about a Hebrew or Greek letter, and this atlas would rather say fewer of them than invent more.