My (Welsh) father always said ach-y-fi, although I didn't know how it was spelled.
I feel this heroic deed should inspire me to clear the space under the staircase where the puppies used to live. I have to leave here soon and it would be unthinkable to leave it, however it needs strength ( sad face #rib) and willpower... I have checked the opening hours of the local dechetterie. Watch this space.
It is definitely ach-y-fi.