Avestan and its Vedic equivalent both derive from Proto-Indo-Iranian *ṛtá- "truth",[REF] which in turn continues Proto-Indo-European * "properly joined, right, true", from the root *.
Avestan druj, like its Vedic Sanskrit cousin druh, appears to derive from the PIE root *, also continued in Persian دروغ / d[o]rūġ "lie", German Trug "fraud, deception".