Some are rarely used anymore and possibly obsolete, but here is my list of interesting, unique and uncommon words.

Think about how you might use one today!

A gogo	As much as you like; galore; plentiful or without limits.
Ab initio	From the beginning.
Abstergent	Cleansing, scouring or having a detergent effect.
Ad Nauseam	To a sickening or disgusting degree.
Addle	To make or become confused.
Agog	Excited and eager to know more or see more.
Bafflegab	Confusing, incomprehensible, or generally unintelligible pretentious language, especially bureaucratic jargon; gobbledegook.
Barbermonger	Someone who frequents the barber’s shop, or prides himself on being dressed by a barber; a man who is concerned with his clothes and appearance in an affected and excessive way; a dandy.
Battologize	To repeat a word, phrase, mannerism, etc. to an excessive and tiresome degree;
Blatherskite	One who talks foolishly at length (or blathers on and on); rambling nonsensical or inconsequential talk or writing.
Borborygmus	the sound of a rumbling stomach; the movement of fluid and gas in the intestinal tract.
Bovine	Having qualities (such as placidity or dullness) characteristic of oxen or cows.
Brabble	Noisy, quarrelsome chatter.
Brusque	Abrupt in manner; blunt.
Bumfuzzle	To confuse or fluster.
Caperlash	Abusive language; to scold.
Carpophagous	Feeding on fruit; fruit-eating.
Chockablock	Very full or crammed full with people or things; brought close together; crowded; jammed.
Churlish	Resembling a churl; vulgar; marked by a lack of civility or graciousness; surly; boorish; rude
Confabulate	To converse informally; chat.
Cornucopia	An abundant, overflowing supply.
Coxcomb	A conceited, foolish dandy; pretentious fop; a man who is too proud of his appearance (or Cockscomb)
Dolosity	Deceitfulness; having hidden malice.
Drivel	Nonsense; boring and unnecessary information; talking stupidly and carelessly; slobbering, drooling or saliva spilling from the mouth or mucus draining from the nose; twaddle, blather, foolishness, gibberish, babble; talking childishly or foolishly; ideas, statements or beliefs that are silly or not true; meaningless talking or thinking.
Estival	Pertaining to summer.
Feinschmecker	A person who appreciates, enjoys and knows a lot about good food; a gourmet.
Finial D’arbre	A Christmas tree topper.
Flapdoodle	An idea, something said or written, or behavior that is silly or stupid; nonsense.
Folderol	Mere nonsense; foolish talk or ideas.
Footle	To talk or act foolishly.
Foozle	To bungle or botch an attempt at something; play clumsily (i.e. in golf).
Frabjous	Wonderful, elegant, superb, joyous, delightful, delicious.
Fractious	Unruly; unwilling to comply.
Fribble	To act in a foolish or frivolous manner; trifle; wasteful.
Gallimaufry	A hodgepodge; confused medley; jumble.
Gambol	To frolic or skip about, as in dancing or playing.
Gelid	Very cold or icy.
Gobbledegook	Language that is usually hard to understand
Grame	Anger, sorrow, harm, misery.
Habiliment	Clothes or clothing.
Hardihood	Boldness or Daring; Courage.
Honeyfuggler	A person who deceives, swindles or cheats someone by talking to them nicely, sweet-talking them, or by using flattery.
Hugger-mugger	In a confused, untidy way that lacks order; secretive or clandestine; disorder or confusion.
Hullabaloo	A clamorous noise or disturbance; an uproar.
Illimitable	Incapable of being limited; limitless; boundless.
Imprimis	In the first place.
Indolent	Wanting to avoid activity or exertion; lazy; slothful.
Jejune	Behavior that is naive, simplistic and superficial; without interest or significance; dull; insipid; juvenile; immature; childish; lacking knowledge or experience; a lack of rewarding or satisfying substance.
Jobbernowl	A Numskull; a Nincompoop; a Block head; a blockish or stupid head; a ludicrous term for the head, usually connoting stupidity.
Joie de Vivre	(pronounced zhwaduh-vee-vruh) “Joy of Living;” a zest for life; a delight in being alive.
Juke	To make a move intended to mislead or deceive (an opponent); to turn or bend quickly, typically to avoid someone or something.
Lethologica	The inability to remember a particular word or name; sometimes called “tip of the tongue” syndrome.
Lickerish	Eager to consume delicious foods.
Logorrhea	Incessant, wearisome or compulsive talkativeness.
Luddite	A person opposed to new technology or ways of working.
Mackle	To blur, as from a double impression in printing.
Mendacious	Habitually telling lies; dishonest; untruthful.
Miscreant	A person who behaves badly or in a way that breaks the law.
Mooncalf	A foolish, absent-minded, idle or freakish person.
Mosey	To wander or shuffle about leisurely; stroll; saunter.
Nowhither	To or toward no place; nowhere.
Nugatory	Useless; futile; of no value or importance.
Omnium Gatherum	A collection of miscellaneous people or things.
Opsimath	A person who begins to learn late in life.
Parsimonious	Unwilling to spend money, use resources or use a lot of something; stingy or frugal.
Pecksniffian	Falsely moralistic; holier-than-thou; hypocritical; insincere; sanctimonious.
Pedantic	Someone who annoys others by correcting small errors, caring too much about minor details, or emphasizing their own expertise especially in some narrow or boring subject matter.
Philistine	A person who refuses to see the beauty or the value of art or culture; one of a race of people who lived in the area near the coast of the southeast Mediterranean in ancient times and were often at war with the Israelites.
Phylactery	Two small, square, black leather boxes that contain Torah verses (Scriptures) written on parchment; in Jewish religious practice, Jewish men 13 years of age and older traditionally wear phylacteries during weekday morning prayers on the left arm or the head (Matthew 23:5); protection.
Perspicacious	Having keen mental perception and understanding; discerning; having a ready insight into and understanding of things.
Piffle	Nonsense; trivial, foolish or senseless talk.
Plebiscite	A direct vote of the qualified voters of a state regarding an important public question.
Poltroon	A coward or craven; an adjective to describe something that is marked by cowardice; sneaky and devious; an idler.
Pollrumptious	Restless, unruly, foolishly confident.
Popinjay	A vain or conceited person, especially one who dresses or behaves extravagantly; a parrot.
Poseur	An insincere person; a person who pretends to be what he or she is not; a person who attempts to impress others by assuming a fake manner, degree of elegance, sentiment, etc., other than their true one.
Puzzlewit	A stupid person.
Quakebuttock	Someone who lacks the courage to do or endure dangerous or unpleasant things; a coward.
Quidnunc	An inquisitive or gossipy person; a busybody.
Rapacious	Aggressively or excessively greedy or grasping; ravenous; usually in a selfish way.
Repine	To feel or express sadness or discontent; to complain; To be fretful or low-spirited through discontent.
Ripsnorter	a person or thing that is strikingly active, remarkably good, forceful, exciting, wild, rambunctious, extraordinary; a humdinger.
Rubberneck	To look about or stare with great curiosity.
Salmagundi	a general mixture; a potpourri; a miscellaneous collection.
Sardonic	Bitter or scornful laughter; disdainfully or skeptically humorous; derisively mocking; humorous in an unkind way that shows you do not respect someone or something.
Saturnine	A slow, gloomy, moody, mysterious person or thing; sluggish in temperament.
Scrofulous	Morally tainted, contaminated and corrupt.
Scurrilous	Making or spreading scandalous claims about someone with the intention of damaging their reputation; obscenely abusive; humorously insulting.
Sepulchre	A building or room where a dead person is buried; a place of burial, such as a tomb, grave, vault, or mausoleum; a receptacle for religious relics, especially in an altar; in the Bible, it indicates a burial.
Skedaddle	To run away hurriedly or flee.
Snollygoster	A shrewd, unprincipled person, especially a politician.
Sop	A weak-willed or spineless person; milksop.
Spancel	A rope used to prevent an animal from straying.
Splendiferous	Excellent, or very beautiful and special; splendid; magnificient;
Spondulicks	Money; cash; a reasonable amount of spending money; spondoolicks, spondulacks, spondulics, and spondoolics are alternative spellings, and spondoolies is a modern version.
Sprechgesang	(pronounced shprekh-guh-zahng) A style of dramatic vocalization intermediate between speech and song; “speech song.”
Sybilline	Mysterious; cryptic.
Tabula Rasa	Anything existing undisturbed in its original pure state.
Tenebrous	Shut off from the light; hard to understand; murky; dark; gloomy; shadowy; obscure.
Tomfoolery	Foolish or silly behavior, act, matter or thing.
Tootle	To move, go, proceed or travel in a leisurely way; a leisurely journey; to play an instrument (like a horn or trumpet) in a casual way.
Treacly	Sentimental in a contrived or unrestrained way; excessively sad, emotional, or nostalgic.
Ulotrichous	Having woolly, curly or crisp hair.
Vapid	Without liveliness or spirit; dull or tedious; lacking flavor or zest; tiresome; lifeless.
Witful	Wise; sage-like; skilled; cunning; ingenious.
Withershins	In a direction contrary to the natural one; contrary; counterclockwise.
Zonked	Exhausted or asleep.