An excellent and free word processor is available in Irish. It is so good that we have decided to dedicate an entire column to it on this website.
There are several very valuable Irish language tools available for LibreOffice:
And, it’s free.
You can find comprehensive information about LibreOffice here.
Note: As OpenOffice.org is not being supported any longer by Oracle, the open source community has decided to independently carry on the project, but under the name “LibreOffice”. It is essentially the same product, at the moment.