The Welsh “defaid” is pronounced “de-VIDE”, by the way (with an “eh” sound in the first syllable, not an “ee”). If you want an f sound, you spell it with two fs – “fforest” being a great example.

English is a pretty simple language to learn, but the pronunciation isn’t part of that simplicity. It’s especially tough to unlearn wrong pronunciations you’ve cultivated for years. In my case (for instance), sword (which I pronounced like “word”) and realm (re-alm).