So how did this etymological nuisance come about? The origins are truly ancient. Back when the English language was still developing, we didn't have a formal English alphabet. We used Latin letters, as we do today. The process of transforming letters from one language to another is what gave us the infamous GH. Let's inspect further.
When used in ancient English, the GH combo did stand for one specific sound we simply don't use today. Some of us can't even pronounce it right. It is something much like a Dutch pronunciation of words like licht (light), nacht (night), acht (eight), or loch (lake). It's a guttural sound produced at the back of the mouth, almost in the throat.
While this sound was widely used in ancient English words, Latin speakers did not use it at all. So naturally, there was no letter in the Latin alphabet to signal this sound! What did our ancient forefathers do to make up for this missing letter? They either used the Latin letter H or the letter 'yogh' used in Older Scots. During the Medieval Era, they settled on GH. The letter 'yogh' is the modern-day equivalent of Y. So this may explain why sometimes the GH combo is pronounced as Y. But where did that F come from?
By the Medieval Era, English pronunciation was already changing. We were transitioning from Middle English to Modern English in a process now called The Great Vowel Shift. Language is an ever-changing thing, and if you've ever talked to a teenager, you probably witnessed it with your own ears. During the Great Vowel Shift, English stopped being a phonetic language (where you say it as you read it) and the changes in pronunciation were vast and rapid (just a few centuries). The transition from a guttural, ancient sound, to the softened F pronunciation, has a lot to do with anatomy. Let professor Mark Sundaram explain:
H/T: MentalFloss
