-st

It seems that apart from Skt. 'ni:d.á', the IE (*ni "down" +
*sd "sit" >) *nizdo "nest" word is exclusively Germanic, Italic and
Celtic. Makes one wonder if the frequent -st suffix of Nordwestblock
names is also zero grade of *s-d- (for semantics, cf
Russian 'sosed' "neighbour"). In that case, those names should be IE
Nordwestblock, or?
I seem to recall there was at least one other IE composite word with
zero grade *s-d-, but I can't remember which?

Torsten