Linking some words in Germanic languages...

[jose.perez3]

Hello I-Es:

I was trying to relate some cognate words in Germanic words that seem to come
from IE *(s)ter "stiff". It seems that the ones which kept the initial s will
give us "st" in English (stiff, starch) and German (stiff, starren). While
those which had lost it will yield "d" in German (Dorn, derb) and the expected
"th" in English (thorn). Can somebody remind me why?. I reckon that it was a
change that applied to other "s" clusters: like *sk in *skel "to cut" -though
not in all the Germanic dialects (E. shirt vs. skirt)- and *sp. I also reckon
that some roots starting with an aspirated plosive could be linked to
s+unaspirated plosive... which would render I-E. initial /s/ a prefix. What
would it indicate?

If somebody has this information on the tips of her/his fingers a brief
explanation and a list of examples it would be very welcome.

I'm also having trouble explaning one of the semantic changes that several
etymological dictionaries. Namely arriving to the idea behind"start, startle,
strike" and G. "stürzen, Umsturz, streiten". Did this happen through an old
word for tail (G. Sterz) that would be first understood as "the stiff one" and
then as "the quick moving one". Somehow that doesn't seem enough. Does anybody
have a clearer idea of that change of meaning?.

What about the several birds that are related to this root? E. "stork,
redstart"; G "Strauss, Drossel". Would you agree with the etymologies that
explain their names because of their being "stiff" or "clumsy"?.

Has anybody linked this root to the one that meant simply "to stand"? IE
*steH2?