How “ar feadh” works
The noun after ar feadh goes into the genitive, the same way it does after a noun: Bhí mé ann ar feadh seachtaine.
Ar feadh is for a period that is finished or measured; for a period still to come use go ceann: go ceann seachtaine, for the next week.
“Ar feadh” in a sentence
Other compound prepositions
Ar feadh in Irish: the questions people ask
What does ar feadh mean in Irish?
ar feadh means for (a length of time), throughout: Bhí mé ann ar feadh seachtaine. I was there for a week.
Does ar feadh take the genitive?
Yes. The noun after ar feadh is in the genitive case: Bhí mé ann ar feadh seachtaine.
Anything else about ar feadh?
Ar feadh is for a period that is finished or measured; for a period still to come use go ceann: go ceann seachtaine, for the next week.