Now that would be a godsend thing. Only I doubt there's no such thing, otherwise it would have been linked here somewhere, in multiple places, I believe.
I've relied heavily on:
- An Foclóir Beag,
http://www.csis.ul.ie/focloir/ - Irish Dictionary Online,
http://www.irishdictionary.ie/home - Focal.ie,
http://focal.ie/Home.aspx An Foclóir Beag is completely Irish, but it has a wide database of words and definitions, it recognizes conjugated verbs, and inflected nouns and adjectives etc.
Irishdictionary.ie has a lot of words and example phrases, but it works half-butt at the moment, so currently you can't search Irish words (the verb search works both ways though). Its verb search wants plain unconjugated forms.
Focal.ie is a terminology database rather than a full-blown dictionary, but all the three fill up each other's shortcomings.
Then there's
http://www.irishionary.com/ which further patches some gaps left over by the three previous.
But back to the original point - these all require manual labor to yield results. No pain, no gain.