Ever wonder why the words through, bough, dough, and rough, are pronounced different despite their similar spelling? Mark this down as another opportunity for that familiar past-time of all warm-blooded Americans: blame the French. It’s an exaggeration, but don’t let petty details get in your way of a good anti-Gaulic rant. From David Crystal’s The Fight for English: How language pundits ate, shot, and left:
Much of the irregularity of modern English spelling derives from the forcing together of Old English and French systems of spelling in the Middle Ages. People struggled to find the best way of writing English throughout the period. … Even Caxton didn’t help, at times. Some of his typesetters were Dutch, and they introduced some of their own spelling conventions into their work. That is where the gh in such words as ghost comes from.
The words in our first sentence come from the Old English words thurh, boh, dag, and ruh.
I was very much under the impression that gh was the standard English transliteration of the now obsolete letter yodh, which was partially glottal and doesn’t exactly correspond to anything in modern English. Hence the variety of ways the pronounciation was changed.
But isn’t yodh a Hebrew letter? Not that there might not be a similar sound in English, if you go back far enough.
I tried to look that up, Custard, but I could find a yodh-gh connection. I think you’re way off the reservation with this one, but you may have heard it from a good source. From what I’ve read about the origin of words, some decent sources come up with wild stories.