• caliginous •
Pronunciation: kê-li-jê-nês • Hear it!
Part of Speech: Adjective
Meaning: Dark, foggy, murky, dim, obscure, gloomy.
Notes: Today's is a lovely word slipping into the caliginous recesses of history. Most dictionaries consider this word archaic, but I found references at Vocabulary.com to uses as recently as 2003 and 2011. Let's not let this one get away from us. We have our choice of two clunky nouns, caliginousness or caliginosity. Both—I am warned by my spellchecker—have already slipped into obscurity.
In Play: The basic sense of today's Good Word is "dark, murky" as in; "Celia Feight enjoys the privacy provided by a caliginous corner in a little cafe in Paris on Rue Barbe Pye." However, we are as free to use this word figuratively as any other: "His arguments are so caliginous I can't follow them at all."
Word History: English acquired this word via French caligineux, which French inherited from Latin caliginosus "misty", an adjective based on caligo "fog, mist". Latin inherited the root of caligo from Proto-Indo-European kal- "gray, white, black" + gen- "give birth to, create". We see the original root in Greek kelis "spot (on an animal)", Lithuanian kalyvas "bright white", and Czech and Slovak kalný "murky, turbid, muddy". Perhaps we could include Russian kalina "guelder rose", which is white. Derivatives often show up as antonyms of their source. English cold and scald derive from the same source. Black shares a source with bleach. (We owe a debt of gratitude today to the word-rescue efforts of Patricia Tancred, William Tupy, and Lew Jury who, over the years, persisted in recommending today's Good if fading Word.)