Q is unique among the letters of the English alphabet in that it always has to be partnered with another letter (not counting loanwords like Quran, Qatar, and Iraq).
Why does it always have to be followed by a U?
First of all, it’s important to note that Q wasn’t always part of the English alphabet. In Old English, words with a kw sound were usually spelt with cw, like cwẽn (queen). Old French though, used qu to represent this sound, and after the Norman conquest of 1066, this became a more and more common feature of English. Though funnily enough, as I touched on yesterday, modern French has lost this pronunciation, and qu in French is basically pronounced like K in English. Which I’m currently finding quite confusing as I’m currently brushing up on my Italian, in which qu is generally pronounced as it is in English.
But where did this digraph (a combination of two letters producing one sound, like ph) come from in French? From Latin, as is so often the case. Latin used qu to represent the kw sound, based on a system originally developed by the Etruscans. They used three symbols to represent the K sound, depending on what vowel sound followed. Before E or I it was gamma (the ancestor of C and G), kappa (which we get K from) before A, and koppa (ancestor of Q) before U.
And that’s why Q and U got stuck together. But while Q is certainly unique in needing U to do its job, there are lots of cases in English of specific combinations that work, and others that don’t. Most of these are what are called consonant clusters, which are exactly what they sound like.
Want to put a T or an L or a P after an S? Fine.
Want to put an R after that ST or SP? Also fine.
Want to put that R directly after the S? Or how about a D?
Don’t be ridiculous.
Want to have four consonants in one word, divided into two pairs? No problem, here’s start! But want to put rt at the beginning of a word? Absurd!
I won’t get into the deep linguistics of why st works at the beginning of a word or the end, but rt only works at the end. Suffice it to say that all languages are restrictive in ways that don’t seem immediately obvious.
So don’t feel too sorry for Q. After all, it’s always got U.