Croman scríbas:

> It is my opinion, however, that the supposed "Lia Fáil"
> carried to Dàl Riada in Scotland was a "Crom-Leac" (in the true
> sense of the word, a "Crom-Stone," a standing stone at the Centre
> of a Circle of Stones, or at the "Centre" of a Tribal territory,
> representing Sovereignty, as Crom is the "King-Idol" according to
> the Dindshenchus)...

The problem with that etymological explanation of "cromleac" is
that altough the word is now found in the Ó Dónaill dictionary,
defined as "cromlech", there is every reason to believe that this
is simply a gaelicization of the original Welsh term "cromlech"
(< crwm 'bent' + llech 'stone').  I laid this out in a message to
Gaeilge-A back in 1997:

> Is cas ar leith "cromlech", b'fheidir, mar thainig an
> focal seo isteach sa Bhearla on gCuimris "crwm + llech",
> agus bhi se in usaid sa Bhreatain sular thainig se go
> hEirinn.  Ar amharai an tsaoil, ta focail ghaolmhara sa
> Ghaeilge, "crom" agus "leac", agus mar sin is furasta
> agus nadurtha Gaeilge a chur ar an tearma seo, ach ni
> fhaca me aon fhianaise riamh go bhfuil se freamhaithe
> go daingean sa teanga Ghaeilge.

The oldest reference to anything like this term in an Irish context
was located by Vincent Morley and reported and commented on by him
on Gaeilge-A:

>    'Near these Druid temples generally stands an odd
>    sort of altar, called Crom-liagh, or Inclined stone.'
>    Thomas Campbell, 'A Philiosophical Survey of the
>    South of Ireland' (Dublin 1778), pp 228-9.
> Tá sé measartha soiléir, déarfainn, gur 'crom-lia'
> seachas 'crom-leac' a bhí i gceist ag an údar. Ceist
> eile é, ar ndóigh, an ag aistriú ó Bhéarla go Gaeilge
> nó ag traslitriú ó Ghaeilge go Béarla a bhí sé.

As far as I know, there is no sign of either "crom(m)lecc" or
"crom(m)lía" in pre-modern Irish.