Here are some selections from Samuel Johnson’s Dictionary, published in 1755. This was not the first dictionary of English, but it was the first to provide quotes to illustrate the usage of words, and it was the most complete up to that point. Most of these words are still "officially legal" words -- they still appear in dictionaries, although they are often flagged as obsolete.
altiloquence: high speech; pompous language
anatiferous: producing geese or ducks
anfractuous: winding, devious, tortuous
anthelmintic: worm-killing
appetence: carnal desire
argillaceous: clayey
appropinquate: to draw near
arrision: the act of smiling upon
astrigerous: adorned with stars
axillary: related to the armpit
balbutiate: stammer
bibacious: addicted to drinking
blatherskite: balderdash
blatteration: producing a continuous clattering noise
caliginous: dim, obscure, dark
constuprate v.t. to violate, defile
crinigerous: adj. hairy
debacchation: n. a blustering or rage
debullition: n. a boiling over
decollate: vt. behead
delirate: vi. to rave
deosculation: n. the act of kissing
depucelate: vt. to bereave of virginity
desidiose: adj. idle, lazy
digladiation: n. combat with swords; any quarrel or contest
discalceation: n. the act of removing one’s shoes
discase: vt. to undress
edacious: adj. voracious; devouring; greedy
elumbated: adj. weakened in the loins
emiction: n. urine
empiricism: n. dependence upon experience without knowledge or art; quackery
ereptation: n. a creeping forth
eristical: adj. relating to dispute; containing controversies
eructation: n. the act of belching
esurient: adj. hungry, voracious
eventerate: vt. to open by ripping the belly
exanimous: adj. lifeless, dead
exiguous: adj. small
expugn: vt. to conquer
facinorous: adj. wicked, atrocious; detestably bad.
facund: adj. eloquent
famble: vi. to hesitate in speech
fasuous: adj. proud, haughty
fatiferous: adj. deadly, mortal, destructive
faxed: adj. hairy. now obsolete
feculent: adj. foul, excrementitious
ferity: n. barbarity, cruelty.
flagitious: adj. wicked, villainous
flammivomous: adj. vomiting out flame
fleer: n. mockery expressed either in words or looks
flexanimous: adj. having the power to change the disposition of the mind
foutra: n. an act of contempt
fream: vi. to growl or grunt as a boar
frigorifick: adj. causing cold
fribbler: n. a trifler
frump: vt. to mock; to browbeat
fungosity: n. unsolid execresence
fustian: n. a high swelling kind of writing made up of heterogeneous, or of words and ideas ill associated; bombast
gallimatia: n. nonsense; talk without meaning
gloze: vt. to flatter, to wheedle; to fawn
grum: adj. sour, surly, severe
gry: n. anything of little value, as the paring of nails
gulosity: n. greediness, voracity, gluttony
habnab: adv. at random; without any rule or certainty of effect
hebitate: vt. to dull, blunt, or stupify
hector: n. a bully, a blustering, pervicacious, noisy fellow
horrisonous: adj. sounding dreadfully
humicubation: n. the act of lying on the ground
hunks: n. a covetous, sordid wretch; a miser; a curmudgeon
idoneous: adj. fit, proper, convenient, adequate
illaqueate: vt. to entangle or entrap
inceptor: n. a beginner
increpate: vt. to chide, to reprehend
indigitation: n. the act of pointing out
infundibuliform: adj. funnel-shaped
insulse: adj. dull, insipid, heavy
iirefragable: adj. uncontroverable
irrision: n. the act of laughing at another
jactitation: n. tossing, motion; restlessness
keck: vi. to heave the stomach; to reach at vomiting
kickshaw: n. something uncommon, fantastical, or ridiculous
knubble: vt. to beat
labify: vt. to weaken or impair
latitation: n. the state of lying concealed
latitudinarian: adj. unconfined in thought
lazar: n. one deformed and nauseous with filthy and pestilential diseases
lief: adv. willingly
linguacious: adj. loqaucious
liplabor: n. action of the lips without concurrence of the mind
luciferous: adj. giving light; affording means of discovery
lucrific: adj. producing gain
luctation: n. struggle, effort, contest
lusk: adj. idle, lazy, worthless
malefic: adj. mischievous, hurtful
megrim: n. disorder of the head
mimographer: n. a writer of farces
minacious: adj. full of threats
moidered: adj. crazed
muliebrity: n. the female analog of virility
multiscious: adj. having a variety of knowledge
mundivagant: adj. wandering through the world
nescience: n. ignorance
nugacity: n. futility; trifling talk or behavior
nullibeity: n. the state of being nowhere
obambulation: n. the act of walking about
obequitation: n. the act of riding about
objurgate: vt. to chide, to reprove
obmutescence: n. loss of speech
obstupefactive: adj. obstructing the mental powers
octonocular: adj. having eight eyes
operose adj. laborious; full of trouble and tediousness
ophiophagous: adj. snake-eating
opsimathy: n. late education
orgillous: adj. proud, haughty
oscitancy: n. the act of yawning
palmipede: adj. webfooted
pash: n. a kiss
peccant: adj. guilty; criminal
pervicacious: adj. spitefully obstinate; peevishly contumacious
philosopheme: n. principle of reasoning; theorem
pickthank: n. an officious fellow, who does what he is not desired; a whispering parasite
pulicose: adj. abounding with fleas
quiddit: n. a subtlety, an equivocation
quodlibertarian: n. one who talks and disputes on any subject
ruderary adj. belonging to rubbish
ruricolist: n. an inhabitant of the country
salutiferous: adj. healthy
sarculation: n. the act of weeding
sciolist: n. one who knows many things superficially
scopulous: adj. full of rocks
scrannel: adj. vile; worthless
scrutation: n. search; examination; inquiry
segnity: n. sluggishness; inactivity
sermocination: n. the act or practice of making speeches
spraints: n. the dung of an otter
stentorophonic: adj. loudly speaking or sounding
sternutation: n. the act of sneezing
stultiloquence: n. foolish talk
subtilize: vi. to talk with too much refinement
supervacaneousness: n. needlessness
swink: vi. toil, drudge
tabefy: vi. to waste
tenebricose: adj. dark, gloomy
tentiginous: adj. stiff, stretched
teratology: n. bombast, affectation of false sublimity
tergiversation: n. shift, subterfuge; evasion; change, fickleness
thrasonical: adj. boastful, bragging
threap: vi. to argue much or contend
tonguepad: n. a great talker
torvous: sour of aspect; stern; severe of countenance
tralatitious: adj. metaphorical; not literal
uliginous: adj. slimy or muddy
visionary: n. one whose imagination is disturbed
yare: adj. ready, eager
yarr: vi. to growl or snarl like a dog
ycleped: called, termed, or named
Lastly, I’d like to add this prodigious sentence from his preface to the dictionary. This is truly one of the monumental sentences of English literature, a towering edifice of words rising into the very heavens. Stock up on your provisions, fill your canteens, and don robust boots before reading this sentence:
That it [the Dictionary] will immediately become popular I have not promised to myself; a few wild blunders, and risible absurdities, from which no work of such multiplicity was ever free, may for a time furnish folly with laughter, and harden ignorance in contempt; but useful diligence will at last prevail, and there can never be wanting some who distinguish desert; who will consider that no dictionary of a living tongue ever can be perfect, since while it is hastening to publication, some words are budding, and some falling away; that a whole life cannot be spent upon syntax and etymology, and that even a whole life would not be sufficient; that he, whose design includes whatever language can express, must often speak of what he does not understand; that a writer will sometimes be hurried by eagerness to the end, and sometimes faint with weariness under a task, which Scaliger compares to the labors of the anvil and the mine; that what is obvious is not always known, and what is known is not always present; that sudden fits of inadvertency will surprize vigilance, slight avocations will seduce attention, and casual eclipses of the mind will darken learning; and that the writer shall often in vain trace his memory at the moment of need, for that which yesterday he knew with intuitive readiness, and which will come uncalled into his thoughts to-morrow.