deriv LSK ETT STT aSTA ALPH OLDHOMEPAGE NEWHOMEPAGE
"Gas" is the singular ending in the sixth group, /GasosAm. So it means basically "of" or "has".
**suhRd- + /Gas → !**suhRdas' "of friend"
caitra- + /Gas → caitra- + /sya' → !**caitrasya "of caitra "
caitrasya gauH "Caitra has a cow"
**vidyut- + /Gas → **vidyutas "of lightning"
/Gas happens to have the same letters "as " as /Gasi /jas /zas —
**vidyut- + /Gasi → **vidyutas "because of lightning"