> Other possibility is that Dian cecht was the "Irishized" form of a
> non-Irish, pre-Celtic name.
I doubt it - it looks perfectly Celtic to me.
> I even don't understand clearly the phonetical changes in Irish. The
Celtic
> *q > Irish c, or Celtic *q > Irish c-w- (cf. coic "five"). Does *q develop
a
> u-glide that modifies following vowel?
> Joao SL
PIE *-kw- gives Common Celtic *-kw- which gives (using Latin orthography)
Goidelic -qu-, Celtiberian -qu- / -cu-, Gallo-Lepontic -p-, and
Brythonic -p-.
Goidelic -qu- develops into Irish c- / -cc- / -ch
Brythonic -p- gives Welsh p- / -b- / -b
Note: PIE *-kw- is partially retained in Gaulish in the ligatures -c "and"
(from PIE *-kwe "and"), -ac "and" (PIE *at[e]-kwe), etic "in addition"
(*eti-kwe). This does not occurr in Lepontic, which has -pe (*-kwe)
SO:
PIE: *ekwos "horse"
Common Celtic *ekwos
Goidelic *equos - Irish ech
Celtiberian equos
Gaulish epos
Brythonic epos - Welsh eb(ol) ["pony"]
-C. Gwinn