1) Ancient iranian language 2) Extinct language of Asia 3) Of the sacred books of Persia 4) Old Iranian language 5) Religious text 6) Religious writing 7) Sacred text 8) Sacred writing 9) Thus spake zarathustra 10) Unicode block 1) Zend 
[Unicode block] Avestan is a Unicode block containing characters devised for recording the Zoroastrian religious texts, Avesta, and was used to write the Middle Persian, or Pazand language. ...
• (a.) Of or pertaining to the Avesta or the language of the Avesta. • (n.) The language of the Avesta; -- less properly called Zend.
A·ves'tan adjective Of or pertaining to the Avesta or the language of the Avesta. -- noun The language of the Avesta; -- less properly called Zend . 
[adj] - of or pertaining to the Avesta (sacred text of Zoroastrianism) 2. [n] - an ancient Iranian language 3. [n] - the script in which the ancient Persian language of the Avesta is written
adjective of or pertaining to the Avesta (sacred text of Zoroastrianism)
an ancient East Iranian language of the Indo-European family, the language of all the Avesta but the Gathas. Cf. Gathic (def. 1).