Siddhaṃ (Sanskrit सिद्धं, "accomplished" or "perfected"; Tibetanསིད་དྷཾ།; Chinese: 悉曇文字; pinyin: Xītán wénzi; Japanese: 梵字, bonji; Middle Chinese (Baxter-Sagart): sit-dom mjun-dziH), also known in its later evolved form as Siddhamātṛkā, is the name of a North Indian script used for writing Sanskrit during the period ca 600-1200 CE. It is descended from the Brahmi script via the Gupta script, which also gave rise to the Devanāgarī script as well as a number of other Asian scripts such as Tibetan script. There is some confusion over the spelling: Siddhāṃ and Siddhaṃ are both common, though Siddhaṃ is correct. The script is a refinement of the script used during the Indian Gupta Empire. The name arose from the practice of writing the word Siddhaṃ, or Siddhaṃ astu (may there be perfection) at the head of documents.
Siddhaṃ is an abugida or alphasyllabary rather than an alphabet because 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 (anusvāra), and the aspirated vowel (visarga). A special mark (virama) can be used to indicate that the letter stands alone with no vowel, which sometimes happens at the end of Sanskrit words.