Eleemosynary was the word assigned to me for my eighth grade Words Project.
Other faves:
Floccinaucinihilipilification
Amanuensis
Antediluvian
Suigeneris
Esoteric. No, wait. Vocabulary.
Smartass 
Décolletage: permitting me to be lascivious and erudite in one fell swoop.
Apocolocyntosis
It was a word made up by someone (probably the younger Seneca) as a title for a work about the making of the emperor Claudius into a God (which would have been Apotheosis, properly). The word is a satiric blend of Greek and Latin, and ought to mean, instead of “deification” = “making into a god”, “making into a pumpkin”. It has this been rendered “Pumpkinification” in many places, including Wikipedia:
The word almost invariably refers to the probably-by-Seneca book, but I used it in my book in the first few pages about a completely different topic*, and I think it helped convince the folks at OUP that I was erudite. Or at least sneaky.
*deceased and lionized Mythologist Joseph Campbell. I’m so mean.
I’m afraid I defined it either ambiguiously or wrongly, though. By “third from last” I really mean “next to next to last.” So that would really be second from last. I think. I can’t count today.
Petrichor - the smell of rain as it first hits dry ground. I love it because I would never have thought there would be such a term, but it is so immediately evocative (the first time I read it I knew exactly what they were talking about) that it’s obviously a necessary word.
I second callipygian, along with its less-flattering mate steatopygian.
I think this is my new favorite word. Even though it isn’t raining right now, your post evoked a sensation of pungent earthy smells. Mmm…Petrichor…
factotum servant with wide-ranging duties
sinecure do-nothing job
frenulum any webbing on the body: between the fingers & toes, underneath the tongue, or from the corona to the raphe of the penis
Formicate - to swarm like ants.
Merkin - a pubic wig.
Orison - a prayer.
Mucilage - glue.
Unguent - ointment.
Abecedarian - in alphabetical order.
Angelet - the metal or plastic cylinder on each end of a shoelace
Interstices - gaps.
Syzygy - an astronomical alignment.
Aww, you guys beat me to callipygian! 
numinous: the sense of the presence of a supernatural or godlike being.
plastiqué (pronounced plas-TEEK): a mallable high-explosive compound such as C4; “plastic explosive”.
chiral: having left-handed and right-handed versions; the antonym of bilaterally symmetrical.
weregild: a wrongful-death settlement.
pintle: old English word for “penis”.
Or, the thing that mates with a gudgeon.
boustrophedon-writing backwards on alternate lines of writing, or, going back and forth on alternate adjacent paths when mowing the lawn (boustrophedonically).
karmadharaya-a word made up of an adjective (or other modifier) and a noun, such as “blacksmith”.
Nitpick Alert.
It’s “plastique”.
And yes, some of my French teachers were martinets.
Is it sad that I was worried one of my two would already be listed? Boustrophedon gets serious points, though. I get to use that word quite frequently. As I use my two favourites frequently:
apotropaic: averting evil.
chthonic: having to do with the earth/soil/underworld. A bonus is autochthonous: being born from the earth of the place where you live.
One of my friends is a techical writer who does write ups for procedures at a pharm company, and keeps threatening to use that in a lab manual. She’s stuck on which piece of glasswear might be most said to resemble a buttock, though.
At the moment my favorite is xanthic, which is fancy way of saying yellowish.
I’m quite partial to using spathic whenever possible. “Danielle, you’re looking positively spathic today!”
Comes complete with its own historical events!
Mine’s quincunx - a pattern of five elements most commonly seen on dice and playing cards.
Nice to see the callipygian getting a nice reception - can’t imagine why…
I forgot another word I really like: synecdoche - I was bummed when that movie, “Synecdoche, New York” came out because the word got misused a lot - kinda like when Alanis hit with Ironic…