A Bactrian Sound Change (OIr. *š > Bactr. h)

This article discusses the twofold reflex of OIr. intervocalic *š in Bactrian, i. e. š / h (G. þ, υ>, ManB. š, h), and seeks to demonstrate that the sound change OIr. *š > Bactr. h occurred only after a back vowel. First, it is argued that OIr. *š is regularly retained in Bactrian after palatal or central vowels, instead of sporadically showing the change towards h, as previously assumed. The two counter-examples to this rule (the pp. ναυαtτο “settled” OIr. *ni-šā̆sta- and the pronominal pl. ending -υανο OIr. -aišanā̆m) are explained as resulting from the paradigmatic levelling on the non-RUKI forms with h from PIE *s, which replaced the sandhi-variants with š. The proposed sound change also helps to clarify the etymology of λρουμινο “enemy” OIr. *duš-manyu-, which is interpreted as another example of OIr. *š Bactr. h after a back vowel and not as an unparalleled case of the change OIr. *šm > Bactr. hm. Finally, remarks on the relative chronology and on comparable sound changes in other Iranian languages are made.