Quellenforschung

Meaning: source research; the study of a work's sources and influences.

Usefulness: 1 (If I'd known this word earlier, this blog would be the Sir Thomas Urquhart Quellenforschung, or possibly the Quellenforschung* Urquhartian.)

Logofascination: 2 (My German etymology is not so strong; the OED links it to a few other words - including quellen for sources - but they're all either very old or very dialect, or both. Unrelated to quell as in quash.)

In the wild: It was the OED word of the day recently, and LTA dug up a few earlier citations.

Manicule

Meaning: the pointing hand symbol F as used in typography, also known as the bishop's fist, pointing hand, mutton-fist*, digit, index, fist or phist. See the Flickr group here for images.

Usefulness: 1 (Manicule is particularly useful as the specific word for this thing; unlike the synonyms above, it has no other meaning. Probably began life as a scribal emphasis - a manual manicule, if you like - so you could always add your own where needed.)

Logofascination: 2 (While the word had been around for a while, manicule was championed in an online essay in 2005, Toward a History of the Manicule. It's interesting, but on the longer side.)

Faciendas

Meaning: Sir Thomas helpfully defines this for us:

Faciendas, are the things which are to be done; faciendum is the gerund of facio.

Faciendum and agendum have similar (if not identical*) meanings, but agendum's busy plural moved with the times and assumed a new meaning.

Usefulness: 1 (If you want a short meeting, ask if anyone has any faciendas. Alternatively, The Horologicon suggests facienda as a more interesting name for a to-do list.)

Logofascination: 1 (Etymologically facienda and hacienda are the same word. Note that Sir Thomas adds the English plural s to the already plural Latin word, although he then uses the singular faciendum a few paragraphs later. He's done this before, so I've added a label for his Latin plurals.)

Quader

Meaning: a Scottish verb meaning to conform, or to be in harmony with; both meanings are extended from its original sense of squaring, as in numbers.

Usefulness: 1 ("Emoticons are not for me; I shall not quader to their laziness." "Of course, hipsters quader as much as the rest of us, but to rather different rules. Boundaries of a negative space - trenchant non-conformism;  or a positive space - a codified sub-culture; are still boundaries.")

Logofascination: 1 (It originates from quadrate, a fancy Latin way of saying square, although the qu- in square is also from the Latin quad-, four, the base of all these words. And, it turns out, cadre, which is what quader started to sound like after I'd said it to myself a few too many times.  I also quite like the fact that squares were associated with conforming in Scotland in the 16th and 17th century, and in the US in the 1940's.)

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.)

Data

Meaning: information, pieces of information

Usefulness: 2 (it's not very exciting, but we keep using it, so it must be useful.)

Logofascination: 1 (because, and only and wholly and solely because, Sir Thomas has the first citation for this word in the OED. He used it in 1645, forty-six years - yes, forty-six - before the next citation*. See graph below for evidence of how ahead of the curve Sir Thomas was on this one.  Some guy is cited under datum from 1630, in a text called Most Easie Way Finding Sunnes Amplitude, which is clearly an early example of spam.)

Orthopantomography

Meaning: it's that dental x-ray (tomography, a particular kind of radiography involving planes, hence tomo - slice, section) where they can see all (a panorama) of your teeth an almost-straight (ortho) line. Was originally called ‘orthoradial pantomography’ which was 'shortened' to orthopantomography.

Usefulness: 3 (unless you work in dentistry or radiography, but it is an impressive sounding word)

Logofascination: 2 (there is something about all those Greek elements lined up together)