During an episode of Fry's English Delight, an amusing BBC Radio 4 programme dedicated to things linguistic, the presenter Stephen Fry set what he called 'a mini vocab test', reading aloud the following list of six words, challenging the listeners to define each in turn:
None of these is in common everyday use, but none of them seems to me to be outlandishly obscure. I expect Fry (or his researchers and writers) wanted to tantalise the audience with words that might just evade the understanding of even the most erudite listeners. He - or they - made no mention of the difference between passive and active vocabularies, yet this is an essential distinction - between words we understand when we see or hear them, but which we seldom or never use in our own speech or writing. Fry's list forms part of my passive vocabulary so, like you, I could come up with an off-the-cuff definition which would pass muster in most contexts, but I can't imagine many normal situation in which I'd employ the words, because simpler options are available and because I want to be understood by my readers and listeners. Perhaps in Fry's case - he is a famously eloquent person - the gap between his passive and active vocabularies is narrow, and both categories are in his case exceptionally large when compared to the average Joe. He's made a career out of it.
When assessing language competence linguists always distinguish between the productive skills (speaking and writing) and the receptive skills (listening and reading). I shan't bore you with the self-evident differences, nor point out that reading and writing are very different skills and that one can read Shakespeare without necessarily writing like him. We cannot write with the same ease and speed and fluency at which readers read - ask any writer, or reader. This is all down to the difference between production (which is hard work) and reception (which may also be hard work, but for different reasons). One of the central flaws in most forms of language assessment is the assumption that a learner doing GCSE French (say) should be equally adept in all four skills - speaking, listening, reading and writing - and assessed accordingly, while in reality even a native speaker would have very different levels of competence. As for my own French say, or German - I can read in both cases immeasurably better than I can write, just as I can order a meal in either language but not follow the average news bulletin (although to be sure that's as much a question of cultural knowledge as linguistic ability).
Back to Fry's list. I was prompted to make my own. See what you make of these. Ready?
If you know the meaning of each well done - but so what? If you don't - again, so what? A wide vocabulary is a Good Thing, of course, although in public life these days we are suspicious of anyone who appears too clever, too literate, too erudite. The power of rhetoric (as Fry pointed out in an earlier episode) is no longer seen as a virtue but a sign of untrustworthy slickness. Fry is unusual - a widely-loved media figure who is smart and endorsed as a sort-of public intellectual, although a cruel critic once described him as "a stupid person's idea of a clever person".
"Coruscating" is frequently misused - it means "glittering" and not (as many people seem to think) fiercely or corrosively, blisteringly critical. It is wrong to say that "a backbencher launched a coruscating attack on the party leader" unless (and it's unlikely, given the standard of parliamentary debate) the attack took the form of a rhetorical tour-de-force.
Enough already. Here's a very funny sketch about language by Stephen Fry and Hugh Laurie in their early heyday. It's called Tricky Linguistics.