Why did you revert my edit on Dehnu's article?
Fragment of a discussion from User talk:Rua
Amphikinetic nouns normally have o-grade of the suffix in the nominative, so you'd expect *déh₂now ~ dh₂n̥wés instead.
Fair enough, but Dehnu clearly was a noun, so it has to have some form of declension. I'll investigate the Celtic form and see what comes up.
And can you explain why *peku doesn't have an o-grade despite being amphikinetic?