悉昙文字

Siddhaṃ, also known in its later evolved form as Siddhamātṛkā, is the name of a script used for writing Sanskrit during the period ca 600-1200 CE.

It descended from the Brahmi script via the Gupta script, which gave rise to the Assamese script, Bengali script, Tibetan script and also inspired Japanese Kana script. Although, here is some confusion over the spelling: Siddhāṃ and Siddhaṃ are both common, but Siddhaṃ is more correct. The script was refined since the Gupta Empire. The name arose from the practice of writing the word Siddhaṃ, or Siddhaṃ astu (「may there be perfection」) as the document heading.

The word Siddhaṃ means 「accomplished」 or 「perfected」. Other names of the script include siddhông, siḍ·ḍhaṃ bonji (Japanese: 梵字) and Chinese: 悉曇文字; pinyin: Xītán wénzi.

Siddhaṃ is an abugida or alphasyllabary rather than an alphabet: each character indicates a syllable, but it does not include every possible syllable. If no other mark occurs then the short 'a' is assumed. Diacritic marks indicate the other vowels, the pure nasal, and the aspirated vowel. A special mark can be used to indicate that the letter stands alone with no vowel, which sometimes happens at the end of Sanskrit words.