Opisthograph

Meaning: etymologically, writing on the back. Cotgrave defines it as:

Papers written upon on both sides.

Usefulness: 1 (This may be my most useful word yet, since it's a fancy name for double-sided printing. I'm thinking of standing by the copier, waiting for someone to ask for help: "Ah, having trouble with the opisthograph function?"*  Can be used to make you sound green - "We've based our sustainability policy on increased use of the opisthograph" - or extended figuratively to irony, sarcasm or double entendre: "I suspect you are indulging in opisthography.")

Logofascination: 1 (While Cotgrave mentions papers, the OED talks of tablets, papyrus and scrolls; I picture an ancient scribe scratching reminders to himself on the back of his work.)

Onychophagist

Meaning: nail-biter, or, if you're feeling etymologically technical, nail-eater.

Usefulness: 2 (I might use this in interviews, when they ask about my weaknesses: "In times of stress I become an onychophagist.")

Logofascination: 2 (Onycho- is from the Greek for nail, as in finger- or toe-nail)

Tumbleweeds

Meaning: Besides the literal meaning, it is used to mark or describe an awkward pause in a conversation, generally because one of the participants has said something particularly foolish or embarrassing. For example: "I made a joke about eating frogs, but it turned out she was French, so, tumbleweeds..."  Also heard/seen as tumbleweed (singular), or tumbleweed moment.

Usefulness: 1 (Even if people haven't heard this before, they will generally grasp what you mean - it's a clear visual image.)

Logofascination: 1 (The logofascination lies in this sense of the word evolving before our eyes; I first saw it on the internet several years ago, but the Virtual Linguist hadn't heard of it in May 2011. Although it's been a visual symbol for some time - see video below - it has flowered into a symbolic term and conversational marker in the last ten years* or so. One never knows with words, but I suspect this symbolism will last, as the visual symbol has.)

Batrachian

Meaning: of frogs and toads.

Usefulness: 1 (depends on culture and context: if you're English, and therefore statutorily obliged to insult the French at least once a week, it would be quite handy. If you're not, its usefulness may depend on your proximity to lakes, swamps or French restaurants.)

Logofascination: 2

Collugency

Meaning: mutual sorrow, shared mourning. 

Usefulness: 1 (Can be used seriously: "the nation's collugency at this sad time..." or not: "The outer suburbs of Melbourne were cast into collugency at Collingwood's elimination from the finals.")

Logofascination: 1 (I am reasonably sure that Sir Thomas invented this one, albeit by Anglicising the Latin collugere.)

Ekskybalauron

Meaning: gold out of dung.

Usefulness: 2 (Admittedly, limited to this blog. I've never said it aloud, and I'm not entirely sure how I would pronounce it. Update: was used to describe the emergence of an apartment from renovations, and I realised it could also be used for financial instruments in which dodgy debt is bundled up to appear attractive. If I work out time-travel, I'll go back about ten years and set up the Ekskybalauron investment firm.)

Logofascination:  2 (Sir Thomas adapted it from the Greek - the work is more commonly referred to as The Jewel, from the beginning of its extremely long subtitle. For more on the topic of gold and dung, and a helpful dissection of the etymology, see here.)

Virgule

Meaning: the forward slash, or /.

Usefulness: 1 (Mainly to intimidate others with your vocabulary. I am saddened that it isn't used more when people give the long form of web addresses. "H. T. T. P. Colon. Virgule. Virgule. W" etc. Would also be a better name for slash fiction - virgule fiction sounds slightly classier, while remaining suggestive.)

Logofascination: 1 (It was once used the way we use the comma, and in Latin it was called the 'little twig', or virgula. The Latin form came into English first, but was mostly replaced when the current form came in via French.)

Fingers of God

Meaning: rays of sunlight breaking through cloud; for photos and various other names, see wikipedia on crepuscular rays.

Usefulness: 1 (you may never get to say it aloud, but from now on, you will see this effect and think of the fingers of God.)

Logofascination: 3 (I am thinking of starting a petition to call them the theodactyls, or theodactylous, along the lines of rhododactylous.)

Axinomancy

Meaning: what it says on the tin - divination by axe.  Various methods are suggested: swinging the axe into something and interpreting the quivering that results; heating an axe-head and interpreting the colours; and the method mentioned in G&P, heating an axe-head with a stone of some sort on top and interpreting the motion of the stone.

Usefulness: 3 (It's rather difficult to think of a figurative use for this. There are extended uses - Rabelais himself has one, quoted below - but they all require having or being around an axe.)

Logofascination: 3 (I wonder who on earth came up with this method, and why they used a perfectly good axe-head for it. Why not heat up random stones and observe them?)

Acronycal

Meaning: happening at sunset; an astronomical term referring to stars which rise at sunset.

Usefulness: 1 (Mainly in poetic senses, although it could also be used to describe one's martini, depending on how early or late sunset is.)

Logofascination: 1 (Besides my being mildly infatuated with star-words at the moment, it's worth pointing out that the slightly odd-looking spelling is due to its etymological parentage. It's not from chronos, as in time, but from acro- and nycti-, or night-rising. Its opposite - rising at dawn - is cosmical.)

Credenda

Meaning: an old theological term - things which are to be believed, articles of faith. Latin plural of credendum.

Usefulness: 1 ("I'm afraid supply-side is credenda in these parts.")

Logofascination: 2 (from the same root - credo - as creed, credential, credence and credenza. The credenza and the credence tables in churches allegedly derive their names from the side table where dishes were tasted for poisons and so forth, before being served to royalty et al, in order to give their food credence. It's in the OED, which is the only reason I'm re-telling such a fantastic story.)

Surquedry

Meaning: Arrogance, presumption, excessive pride.

Usefulness: 1 (A word that can be disguised with tone: "Very impressive, sir: I've seldom seen surquedry so splendidly displayed.")

Logofascination: 1 (An old word, come to us via Old French from the Latin supercogitare, or over-think, as in think too much of oneself - overweening is the same concept via Old English. Overweening surquedry is therefore a satisfyingly tautological phrase. Surquedry has the rather lovely adjectival forms surquidant and surquidous.)

Bletting

Meaning: I try not to borrow OED definitions too much, but sometimes they're too poetic to resist:

To become ‘sleepy,’ as an over-ripe pear, a special form of decay to which fleshy fruits are subject.

Some fruit - medlars, for example - are inedible until this process has completed.

Usefulness: 2 ("Despite reaching nominal adulthood at 18 or 21, most of us require several years of bletting before we reach full maturity. In some cases, decades.")

Logofascination: 2 (I always wonder who was the first to try that over-ripe fruit. The definitions and etymologies suggest that the French blet / blette / blettir which John Lindley referred to meant sleepy, but from what I can see it actually means over-ripe, or perhaps, originally, bruised.)

Permeate

Meaning: to pass through, to spread through, or to pervade. Also has a technical sense in the dairy industry, meaning a watery by-product which contains lactose, water, vitamins and minerals; i.e. some of the things that permeate milk. There have been several scare-campaigns in Australia about the use of this product to even out fat or sugar levels in milk.

Semantically impossible.

Usefulness: 5 (Only for the second meaning, and my apologies in advance for the rant you're about to be subjected to. My language snark levels are actually decreasing with age and education, but blatant contradictions of meaning frustrate me no end, particularly when inflicted by not-very-good coffee chains far too early on a Saturday morning. Given the definition above, how can anything be free of permeates, except possibly the physicists' hypothetical ideal vacuum? Even used in its technical dairy sense, milk permeate comes from milk, and everything in it is in milk - hence the name permeate - so saying that various milks are permeate free is ridiculous. If it actually is permeate free, it's not milk, whatever milk is - and if you'd like more discussion on that, I recommend the Gruen Transfer milk episode. /rant)

Logofascination: 1 (I am interested in how long permeate has had this meaning in the dairy industry, and whether I'm right in thinking it's linked to the geological use of permeate, but am yet to find an answer.)

Cardiognost

Meaning: one who knows the heart. Thomas Blount pointed out that this is "an attribute peculiar to God alone", however we might wish it otherwise.

Usefulness: 2

Logofascination: 1 (Another of my irrational attachments.)

Libanomancy

Meaning: divination by incense smoke.

Usefulness: 3 (It has some rather useful cousins, though: libaniferous - yielding incense, and libanophorous or libanotophorous - producing incense. Come Christmas, I'll be mentioning the libanotophorous Magi every chance I get.)

Logofascination: 1 (Libano is from the Greek for incense, and I think frankincense specifically, but can't quite confirm.)

Enodandum

Meaning: Sir Thomas kindly provides definition and etymology in the Lexicidion at the end of Trissotetras:

that which is to be resolved and explicated, declared, and made manifest; from enodo, enodare, to unknit, or cut away the knot. 

Usefulness: 1 ("What is my first enodandum for the day, Alex?" In the quote below, Sir Thomas pluralises it as enodanda but then adds the English s as well: enodandas.)

Logofascination: 1 (While this is not yet in the dictionary, enode - to loose or untie; enodous - free from knots; and enodable - capable of being freed from knots; are all in the OED, and should be used more often.)

Tachygraphy

Meaning: fast writing - includes, but is not limited to, shorthand.

Usefulness: 1 ("The good doctor's tachygraphy is, unfortunately, undecipherable.")

Logofascination: 1 (Stenography is narrow writing; this would be crucial if you were trying to save paper.  Stenography can also be fast, but if I'm reading my dictionaries correctly, tachygraphy was applied to cursive, since it's faster than non-cursive - it's possible this only applies in paleography, the study of ancient writing.)

Supererogate

Meaning: to do more than required, to go beyond; originally a Catholic term referring to someone performing good works / penance / prayers to earn merit for another (e.g. a deceased relative).

Usefulness: 1 (Sarcastically: "Well, no need to fear supererogation in this office." To confuse waiters: "Your supererogation has not gone unnoticed.")

Logofascination: 2

Dromomania

Meaning: the urge to wander as a psychological condition; used figuratively to describe wanderlust. 

Usefulness: 2 (I prefer fernweh, which captures both the wandering spirit and the sharp pangs one experiences back home, without the suggestion of psychosis)

Logofascination: 1 (Thanks to dromos being Greek for course or running, it is part of a spectacularly diverse etymological family which includes the dromedary, palindrome, syndrome and hippodrome.)

Cricket

Meaning: My favourite thing, but if you'd like a longer definition, the online Oxford says:

an open-air game played on a large grass field with ball, bats, and two wickets, between teams of eleven players, the object of the game being to score more runs than the opposition

Usefulness: 1 (if you talk about it as much as I do. I'm rather impressed I've done 77 posts without mentioning it here.)

Logofascination: 2 (etymology unknown, and about as many theories as people to ask: the Inky Fool talks about a possible connection to stool-ball, wiktionary features someone else's theory about Dutch origins, and there's a bunch more theories over at wikipedia.)

Sternomancy

Meaning: fortune-telling by the breast-bone, or 'markings or bumps on the chest or breast bone'.

Usefulness: 3 (One could use it as Rabelais does, to remark on the size of someone's stomach, or to describe some of the measurements they do in gyms and doctor's rooms and things; they are supposed to be predictors of the future, one way or the other.)

Logofascination: 3

Natatory

Meaning: as a noun, this means a place to swim (generally a pool of some kind, although not always) and as an adjective it applies to things of, or relating to, swimming.

Usefulness: 1 ("Out the back we have our humble natatory." "Urquhart Bluff Beach* seems natatory, but has some dangerous rips." And then there's all the things it could have been applied to during the Olympics: "A dearth of medals natatory has disappointed the nation.")

Urquhart Bluff Beach: not natatory.

Logofascination: 1

Hippodramatic

Meaning: the dramatic arts associated with a circus; the drama of a circus.

Usefulness: 1 (This word suggests hysteria and bathos and a grand fuss. Asking someone to stop all the hippodramatics, or describing an event as terribly hippodramatic, is self-explanatory.)

Logofascination: 2 (Despite the hippo-, this doesn't seem to have arisen from a horse link - it's possibly from association or confusion with hippodromes. Hippodramas exist, but are apparently dramas featuring horses.)

Label

Meaning: Originally meaning a band or strip of cloth, the meaning evolved through tatters to ribbons, on into strips of paper used to add notes or hold a seal, and then out into a multitude of figurative uses - record companies, tags on clothing, stereotypes, and even categories on blogs.

Usefulness: 2 (I've just added a labels gadget to this blog, that's how useful they are)

Logofascination: 3 (It's a word so old its etymology is murky; tag has a similar evolution - from something hanging off clothes into a way of finding things in an electronic medium.)

Triboulet

Meaning: Cotgrave:  

a slovenlie fellow, one that usually weares his hose ungartered, and shooes untyed; also, the name of a famous foole belonging to King Francis the first; and thence, any fop, cokes, ridiculous ninniehammer, or laughing-stocke.

Triboulet was indeed a fool to Francis I, not to mention Louis XII. As well as this derogatory French term, he was apparently an inspiration for Rigoletto .

Usefulness: 1 (of myself, mainly, although technically I think that would make me a triboulette)

Logofascination: 2 (I admit to cheating here, and picking up a French word rarely used in English - wiktionary lists it, but not the OED.)

Gyromancy

Meaning: much as I'd like it to mean spinning around until you fall over (which is what Rabelais appears to suggest), serious divination by this method apparently involves walking around a circle of letters... until you fall over. Or, more boringly, spinning a coin until it falls over. Cotgrave hedges his bets with 'divination by circles', which could apply to any number of things.

Usefulness: 1 (Could be applied to games of spin-the-bottle, but I'm going to talk to our safety person about how we can implement this at work; it'd be much more fun that tossing a coin. )

Logofascination: 3 (the concept is interesting, the word less so, and you're probably still digesting all that cheesecake from yesterday.)