We do not currently know of any synonyms for candrabindu.
The noun candrabindu is defined as:
A diacritic used in the Devanagari (ँ), Bengali (ঁ), Gurmukhi ( ਁ), Gujarati (ઁ), Oriya (ଁ), and Telugu (ఁ) scripts. It usually indicates that the previous vowel is nasalized. Shown here over the letter "ka" (or in the case of Telugu, after the "ka"):