Precisely.

Assuming there's no evidence either way, and assuming there is no evidence to suggest it is of another origin, we cannot rule it out.

It is believed not to be Indo-European as "madradh" has no known Indo-European cognate in any of the Indo-European languages, whereas "Cú" has. This field of research, "Goidelic Substrate Hypothesis", is only in its initial stages, but its an exciting prospect. Some other words: "Sionnach" (Sinnach)- Fox has no Indo-European origin, whereas "Criomthann" (Cremthann/ Crimthann) does. "Bradán" (bratán) has no related word in any Indo-European lexicon, whereas "Eó" does. O.Ir "Pattu"- hare doesn't either whereas, "Giorr(fh)ia" (Girfhiad) does. Some names, placenames and Landscape features (rivers (life) etc.. though its believed some rivers are named after Goddesses) exhibit characteristics that are not of an Indo-European origin. So either they were adopted into Goídelc before or they developed independently after the arrival of a Celtic language or there cognates haven't been discovered yet.

Gearóid Mac Eoin in his essay, "What language was spoken in Ireland before Irish", provides an interesting discussion on the placenames' argument, using /f/, when its clear /f/ is not the result of grammatical mutations of *sw or as a result of in-coming words from Latin circa 7th century AD ,where /f/ was kept. Originally the Irish could not pronounce /f/ until circa 7th century A.D. Latin words beginning with /f/ before the 7th century became "s" e.g furnus (sorn)= oven, "us" knocked off because of apocype (c.500+) and fenester (Old. Ir and Welsh senester)= fuinneog etc...

He also offers one of the possible theories for who brought and when a Celtic language/ Indo-European language arrived in Ireland, namely through Britain. The Britain theory was also the opinion of Cormac Mac Cuillennáin c. 900 A.D, possible composer of the Sanas C(h)ormaic which offers the first etymological study of Irish relying on Welsh. The first etymological study of any European languages outside of the classics. Another theory is the Irish language arrived in Ireland as a result of the Celtiberians through "Cumalitive Celticity" (the invasion theory is no longer widely accepted as the archaeological evidence i.e celtic material culture- La Tène art and repousé design metal working is unsubstantial.There has never been a chariot discovered in Ireland (though Irish literature is riddled with references to chariots (though it is estimated only 1% of all archaeology is recovered). The Celtiberian theory is offered as an explanation as to why Irish is Q-Cheltic and British is P-Cheltic also.

http://opus.kobv.de/ubp/volltexte/2007/ ... ontact.pdf

pg. 113

Though I agree it was probably a sweeping statement to suggest "madradh" is not of I.E origin, apologies on that...just found it interesting to note that there is no known cognate in an I.E language. And until there is the theory will persist. as an_t-uaithneach said its impossible to prove a negative . I was a aware of the unkown origins of "dog". I believe I heard that on QI .

QI http://www.youtube.com/watch?v=zKSf7H8gU0k (12:58)

Some comment made by Ava Wilson on the You Tube clip:

Dog doesn't really seem to be an etymological mystery:
"From Middle English dogge, from Old English docga (“hound, powerful breed of dog”), a pet-form diminutive of Old English *docce (“muscle”) (found in compound fingerdocce (“finger-muscle”) with suffix -ga (compare frocga (“frog”), picga (“pig”)), from Proto-Germanic *dukkōn (“power, strength, muscle”). In the 16th century, it superseded Old English hund and was adopted by many continental European languages."
Ava Wilson

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