I came across a wonderful word in Welsh today – hollallu [hɔɬˈaɬɨ] – which means omnipotence or almightiness. It is a portmanteau of (h)oll (all, the whole, everything, everyone) and gallu (to be able (to), have power (to), can, be able to accomplish (a thing)), and there are a couple of variant forms: ollallu and hollalluogrwydd.
Related words include:
– hollalluedd / ollalluedd = omnipotence
– hollalluog / ollalluog = omnipotent, almighty, all-powerful; the Almighty.
Source: Geiriadur Prifysgol Cymru / A Dictionary of the Welsh Language
So I have come up with a Welsh version of Omniglot based on these words – (h)olliaithadur, which combines (h)oll with iaith (language) and the suffix adur (denoting a tool or thing) as in geiriadur (dictionary or “words tool/thing”).