Avestan ashavan is a Zoroastrian

Zoroastrianism

Zoroastrianism is a religion and philosophy based on the teachings of prophet Zoroaster and was formerly among the world's largest religions. It was probably founded some time before the 6th century BCE in Greater Iran.In Zoroastrianism, the Creator Ahura Mazda is all good, and no evil...

 theological term. It literally means "possessing aša

Asha

Asha is the Avestan language term for a concept of cardinal importance to Zoroastrian theology and doctrine. In the moral sphere, aša/arta represents what has been called "the decisive confessional concept of Zoroastrianism." ...

", hence "possessing truth" or "possessing righteousness", but has further implications:

• It is an epithet of Ahura Mazda
  Ahura Mazda
  Ahura Mazdā is the Avestan name for a divinity of the Old Iranian religion who was proclaimed the uncreated God by Zoroaster, the founder of Zoroastrianism...
  
   (Yasht
  Yasht
  The s are a collection of twenty-one hymns in Younger Avestan. Each of these hymns invokes a specific Zoroastrian divinity or concept. Yasht chapter and verse pointers are traditionally abbreviated as Yt....
  
  1.12). The term may then be applied to anything within the domain of Ahura Mazda and/or Aša
  Asha
  Asha is the Avestan language term for a concept of cardinal importance to Zoroastrian theology and doctrine. In the moral sphere, aša/arta represents what has been called "the decisive confessional concept of Zoroastrianism." ...
  
   (i.e. all of Creation), and excludes only that which is not drəgvant "possessing lie" (YAv
  Avestan language
  Avestan is an East Iranian language known only from its use as the language of Zoroastrian scripture, i.e. the Avesta, from which it derives its name...
  
  : drvant).

• With respect to mortals and in an eschatological and sotereological context, ašavan is also a quality that can be acquired in life. Then, having acquired the qualities of an ašavan, one becomes an ašavan (through "blessed union with aša") after death. (See also: aša: in eschatology and sotereology). Zarathushtra is said, following Tradition to be the only Ashavan that has become an Ashavan during his life.

• Ašavan may be used to denote any follower of the "Good Religion." This is the most common use of ašavan, applicable to any who walk the "path of truth" (Yasna
  Yasna
  Yasna is the name of the primary liturgical collection of texts of the Avesta as well as the name of the principal Zoroastrian act of worship at which those verses are recited. The Yasna, or Izeshne, is primarily the name of the ceremony in which the entire book is recited and appropriate...
  
  68.12 and 68.13). In this context, Ašavan is frequently translated as "righteous person" or "blessed person." This general meaning of ašavan is preserved in Middle Iranian
  Iranian languages
  The Iranian languages form a subfamily of the Indo-Iranian languages which in turn is a subgroup of Indo-European language family. They have been and are spoken by Iranian peoples....
  
   languages as Pahlavi ardav.

The sotereological meaning of ašavan is also evident in Xerxes' daiva inscription, an Old Persian text (XPh). That the souls of the dead dwell in the radiant quarters of Truth (Yasna 16.7) also has Vedic parallels: According to the RigVeda, the seat of truth is located in the other world. This next-world implication of ašavan is preserved in Middle Iranian

Iranian languages

The Iranian languages form a subfamily of the Indo-Iranian languages which in turn is a subgroup of Indo-European language family. They have been and are spoken by Iranian peoples....

 languages as Pahlavi ahlav.

The linguistic cognate of Avestan ašavan is Vedic ŗtáavan, which however has some functional differences vis-à-vis the Zoroastrian term:

• The dichotomy of the ašavan and the drəgvant is not attested in the Vedas.
• In the Vedas, ŗtá- is hidden from ordinary mortals and only initiated seers are allowed to possess ŗtá- (become ŗtáavans). In contrast, in Zoroastrianism any mortal may strive to possess aša.