If you don’t know this word, it’s no great surprise; it is circulated mainly among the clerisy (that is, the literati – people of learning and illumination, and in particular people of learning about illumination, especially architects). I first saw it in an article in The Buffalo News.
No, no, I’m not being silly. The article was on the new terminal for the Buffalo Niagara International Airport, at that time soon to be under construction (it’s been open for several years now), and for whatever reason it mentioned that the terminal was to have clerestories, but didn’t explain what they were.
I knew it had something to do with fenestration, but beyond that I was met with frustration. I also guessed that it was pronounced with four syllables, and wasn’t sure if the stress was on the first (/klɛ/) or the second (/rɛ/). So, of course, at my next chance, I looked it up. And the first thing I learned was that it actually has three syllables and is pronounced like “clear story”.
The second thing I learned, of course, was what a clerestory is: a high window, in this case (as often) a window in a raised section of roof that lets light into interior spaces – not a skylight, which is set into the roof without interruption, but rather one of those windows of which the archetypal image of a factory has many, giving its roof a sawtooth appearance. (In the original sense, it is a set of high windows in a cathedral that allow the centre of the nave to be well illuminated.)
So raise the roof! That shed sufficient light on the matter. But, now, how do we come to have this word in this form? Ah, well, it turns out the story for that is not quite clear. The clere is really an old spelling of clear, in this sense meaning “lit, light-bearing” because the sense “unobstructed” did not exist for clear in the early 1400s when this word was first written down. We would assume that the story is as in a level of a building (what we prefer in Canada to spell storey), but the problem is that that sense of story is otherwise unknown until a couple of hundred years later. So we don’t really know the story here altogether.
Now, I don’t know about you, but I find that the spelling of this word obnubilates or even obfuscates its morphology for me. I keep wanting to treat it like a word like refectory or consistory or conservatory; it makes me think as readily of clerisy and Clerihew as of clear. Habituation to clear and to the various -(t)ory words just makes a “clear story” pronunciation seem wrong, because I’m not really used to this word.
Mind you, the spelling clearstory does exist too. But, now, knowing that the spelling clerestory exists, most English speakers will feel by reflex that clerestory must be the “better” spelling precisely because it is the less expectable – the perverse historical development and present patterns of our spelling make us tend to think “marked” (irregular) forms must be more authentic, formal, better. (Hence, for instance, many people will think an historic must be correct, when in fact for anyone who pronounces the h it’s actually not.) Such lines of thought make it desirable to have some means of shedding light into the middle of the messy factory floor of English usage.
Or the busy airport, if you will. Actually, as many Torontonians will tell you, Buffalo Niagara International Airport is nice for being considerably less busy than Toronto’s Pearson International Airport. And cheaper to fly out of if you’re going to the US. And even cheaper to get to if you take the bus. None of which has anything to do with clerestory in particular. But should you happen to go there, you will not need to look up clerestory. You can just look up.