You know why I spend so much time online? ’Cuz I’m yuky.
Not yucky! Yuky! I have a yekth to know!
Look, scratch that. …No, I don’t mean disregard it. I mean scratch it. It’s a yuke. Which means an itch. That should be obvious, right?
Here’s how it goes. Yuky (that’s with a long u) is a word that (as of 1921, anyway) is supposedly still used in Scottish and northern English dialects to mean ‘itching’ or, by extension, ‘itching to know’; it comes from yuke, ‘itch’, noun and verb. Yekth is an obsolete form of the word with a -th signifying a health condition (pruritus, i.e., itchiness). All of those and itch are from the Old English word for ‘itch’, giccean, which in its turn comes from a Proto-Germanic word reconstructed as *jukjǭ, which is also the source of Dutch jeuk (‘itch’, noun) and German jucken (‘itch’, verb).
I’m sure at this point you’re altogether yuky to find out how giccean became both yuke and itch. The first thing to know is that in Old English – like in modern Italian – c before i or e was said like “ch” as in child (in fact, the Old English word for ‘child’ is cild). This is because in Old English, c was “k,” but before those high front vowels the tongue’s point of closure moved forward, so far forward that it had increased constriction even after saying it, and ultimately it became like “ch” (try saying “cute” really really emphatically and you may begin to get a sense of how this could happen). That’s also how Classical Latin c, which was always “k,” got to the “ch” of Vulgate Latin and Italian. (Later on, English respelled that sound as ch and picked up the French style of making c sound like “s” in the same position. Old English didn’t have the letter k and French seldom uses it, so by the time it got into heavy use in English that business was all over, and on the other hand English didn’t get into the Scandinavian style of making klike “sh” or the ch in German ich before high front vowels.)
The second thing to know is that the same thing happened to g, except in Old English (unlike in Modern English) it didn’t stop at “j”; it released even further and continued on to a “y” sound, which is also what it does in Swedish before high front vowels. Some languages (including some Latin American varieties of Spanish) treat the “j” and “y” sounds as interchangeable. I’ll skip the details of what happened to it in English after that, because it’s not a short digression, but if you’re yuky about it you can Google it easily enough.
The third thing to know is that while the Old English word didn’t have an “u” or “ü” sound in it, it had passed through “ü” on the way from “u” to “i” (I hope it’s easy to see how that could progress), and other Germanic languages still had the “u,” and that seems to have influenced the yuke version.
So. Got that? The Old English word giccean was pronounced like “yitchan,” but the c was considered to be a “k” that before e and i got a little scratchier (this is also why in yekth it’s a k), and the i came from a u that was brought back in the northern version. The g was said like “y” and in the southern version (which became the standard version) disappeared altogether (you can see how “yitch” could become just “itch,” right?).
By the way, Old English did have a word that sounded like “itch.” It’s the word ic, which was the first-person singular pronoun – in other words, I. Yes, yes, I was surprised and doubtful the first time I learned that – surely the c would be like “k” or like German ch, no? No. – but that is what you get when you are yuky about language. Yekth, that’s right.