Wikipedia
Chandrabindu (meaning "moon-dot" in Sanskrit, alternatively spelled candrabindu, chandravindu, candravindu, or chôndrobindu) is a diacritic sign with the form of a dot inside the lower half of a circle. It is used in the Devanagari (ँ), Bengali , Gujarati (ઁ), Oriya (ଁ), Telugu (ఁ), and Javanese (ꦀ) scripts.
It usually means that the previous vowel is nasalized. It is represented in Unicode as U+0901 in Devanagari, U+0981 in Bengali, U+0A81 in Gujarati, U+0B01 in Oriya, U+0C01 in Telugu and U+A980 in Javanese. There is also a general-purpose combining diacritical mark COMBINING CANDRABINDU code point U+0310 (◌̐), but that is intended for use with Latin letters in transliteration of Indic languages.
In Hindi, it is replaced in writing by anusvara when it is written above a consonant that carries a vowel symbol that extends above the top line.
In Classical Sanskrit, it seems to occur only over a lla conjunct consonant, to show that it is pronounced as a nasalized double l, which occurs if -nl- have become assimilated in sandhi.
In Vedic Sanskrit, itis used instead of anusvara to represent the sound anunaasika when the next word starts with a vowel. It usually occurs where in earlier times a word ended in -ans.
It should not be confused with another symbol, the fermata, which looks like an upside-down chandrabindu; it is an element of musical notation.