adj. misty, dim, obscure, dark (from Oxford American Dictionary)
I’d like to believe that every idea has a perfectly suited word, but the problem would be that no man could remember them all. Sometimes there is a word that simply uses its utility because we would never use it enough to burn it into memory. Therefore, even if the speaker could recall it, it would be unlikely that the listener would know it. This seems to be one of those words.
It came to me via Patrick Burns, who found it from the interesting linguistic site, languagehat.com. They found it in a Roberts Graves quotation, precisely about people who use words that “one expects to meet only in books.”:
Professor Edgeworth, of All Souls’, avoided conversational English, persistently using words and phrases that one expects to meet only in books. One evening, Lawrence returned from a visit to London, and Edgeworth met him at the gate. “Was it very caliginous in the Metropolis?”
“Somewhat caliginous, but not altogether inspissated”, Lawrence replied gravely.
From what I can tell, languagehat.com is written by a very well educated polyglot. It can be very dense, but it certainly is evidence that there are intelligent blogs on the internet.