I have a great love of words, and I will include here some of my favourites - those that do and don't exist (most of them do); and those that I think should be used more widely. Some I like for the meaning, some just for the beauty of the word.

Hippopotomusesquipedalian - Pertaining to a very long word.

Pseudoultraantidisestablishmentarianists - Those who feign to be avid opponants of the dissolution of the established religeous base

Gormful - Everyone knows what it is to be gormless, and many people go around with a constant lack of gorm. But why do we never notice when people are not gormless, when they are bounding with gorm, are gormful?

Nosethirls - The old word for nostrils. And so much nicer. My English teacher pointed this out to me in A level English, whilst studying The Miller's Tale.

Discombobulate - No idea what it means but it's a great word.

Bizzarre - Its odd.

Equus - Of horses (And a very odd Peter Schaffer play).
 

Futtocks - Old beams in ships.

A (anyone remind me of this one?)
Biopsy - These three words are the only English 6 letter words with all the letters in alphabetical order!
Chintz

Facetious - My favourite 'all the vowels in order' word, mainly because knowing that, is.

Syzygy - Got this from Graeme's page (below). No idea what it is (probably good in scrabble).

Szasz - Thomas Szasz, and antipsychiatrist.

Logogogue - One who legislates on words

Zoara - insomnia

Dysrhythmia - jet lag

Pandiculation - stretching and yawning

Qwerty - a type of keyboard - q sans u

Coq - feathers on a hat

Zaqqum - a tree with bitter fruit (double q!)

Praline - a confection

Committee - three double letters

Bookkeeping/er/s  - the only word (I'm told) with three double letters in a row

Kempt - we never hear of this, people are always 'unkepmt'

Promiscuous - composed of all sorts

Aphallatosis - disorder resulting from a lack of sex

Neolagnia - first appearance of sexual desire

Amphigory - poetry which looks meaningful but is actually nonsense

Anthropophilic - mosquitoes which prefer human blood (i.e. of good taste, but appalling manners)

Bibliobibuli - people who read to much (H.L. Mencken)

Boustrophedon - writing which runs left right, then right left

Camouflet - an underground cavity

Chad - the tiny bits of paper left from punch cards (meaning more interesting than word, here)

Charrette - the rush to reach a deadline (which I do too often)

Coruscation - a flash of wit

Defenestration - a classic

Dontopedalogy - aptitude for foot in mouth syndrome (Prince Philip)

Duende - the power to attract by charm

Ejaculatirium - use yer imagination!

Exoteric - another one we don't hear enough

Feuterer - one with a dog (who thinks of these words???)

Formication - the feeling that ants are crawling on you

Illeism - referring to self in the third person

Omphaloskepsis - the act on contemplating one's navel (an interesting pasttime)

Oxymoron - uses xy, must be good

Pognophile - lover of beards

Pygalgia - soreness of the buttocks

Incongruous - standing out

Snurp - to become wrinkled or shrivelled

Thurification - the act of burning incense

Yerk - to beat vigorously

Incongruous - standing out

Logamnosis - mania to recall lost words

Logion - Maxim of a teacher

Logodaedalus - one who is cunning in words

Logodaedaly - arbitrary coining of words (see Taussikograph and Taussikism)

Logofascinated - fascinated by words

Logolatry - worship of words

Logology - study of words

Logophile - lover of words

Logastellus - one who's enthusiasm for words is greater than his knowledge of them (John McClellan, 1970)

Logocide - to kill a word (Dmitri Borgmann, 1965)

Comiconomenclaturist - one who collects funny names

Moria - morbid impulse to make jokes

Risibility - the inclination to laugh at what is ridiculous, incongruous or absurd

Verbigeration - habit of frequently repeating favourite words, verbigeration, verbigeration verbigeration

Kakorrhaphiophobia - fear of failure

Basostasophobia - standing

Medomalacophobia - loosing an erection during coitus

Ophthalmophobia - being stared at

Phthisiophobia - tuberculosis

Onomatomania - attaching a significance to certain words

Phlebotomomania - bloodletting

Onychotillomania - neurotic picking of the nails

Brrr - expression of cold

Crwth - a musical instrument

Hsh - expression to urge silence

Phpht - expression of annoyance

Tch - expression of vexation

Tck - expression of surprise

Tsk - expression of annoyance

Tsktsk - to say tsk

Tst - expression to urge silence

CAUTION - Citizens Against Unnecessary Tax Increases and Other Nonsense

COYOTE - Call Off Your Old Tired Ethics (in support of prostitutes)

CREEP - Committee to RE-Elect the President (Nixon)

GOOD EGGS - Geriatric Order of Old Dolls who Encourage the Generation Gap Single-mindedly

NOSE - Neighbours Opposing Smelly Emissions

OGLE - Organisation Getting Legs Exposed

SHAMES - Society to Humiliate, Aggravate, Mortify and Embarrass Smokers

SUCKER - Society for Understanding Cats, Kangaroos, Elks and Reptiles

CLITORIS - Campaign For The Liberation ... And Their Reintegration Into Society (from Red Dwarf)

KABOOM - the one from The Naked Gun

FUMTU - Fouled Up More Than Usual

TASFUIRA - Things Are So Fouled Up Its Really Amazing

GRUMPIE - Grown Up Mature Person

SWAG - Scientific Wild Ass Guess

BURMA - Be Upstairs Ready My Angel

FICTIONS - Forgivable Inventions Created To Impress ONe's Spouse

LAWYERS - Losing, As Winning, Yet Earning Remunerations Safely

Dzo - yak and cow
Zum - yak and cow
Yakalo - yak and buffalo
Zobo - zebu and yak
Hinny - stallion and she-ass
Mule - male ass and mare
Zebrula - zebra and horse
Geep - goat and sheep
Liger - male lion and female tiger
Tigon - male tiger and female lion

Jumart - cow and horse

Acetylseryltyrosylserylisoleucylthreonylserylprolylserylglutaminylphenylalanylvalylphenylalanylleucyl serylserylvalyltryptophyalanylaspartylprolylisoleucylglutamylleucylleucylasparaginylvalylcysteinyl
threonylserylserylleucylglycylasparaginylglutaminylphenylalanylglutaminylthreonylglutaminyl
glutaminylalanylarginylthreonylthreonylglutaminylvalylglutaminylglutaminylphenylalanylseryl
glutaminylvalyltryptophyllysylprolylphenylalanylprolylglutaminylserylthreonylvalylarginylphenyl
alanylprolylglycylaspartylvalyltyrosyllysylvalyltyrosylarginyltyrosylasparaginylalanylvalylleucyl
aspartylprolylleucylisoleucylthreonylalanylleucylleucylglycylthreonylphenylalanylaspartylthreonyl
arginylasparginylarginylarginylisoleucylisoleucylglutamylvalylglutamylasparginylglutaminyl
glutaminylserylprolylthreonylthreonylalanylglutamylthreonylleucylaspartylalanylthreonylarginyl
arginylvalylaspartylaspartylalanylthreonylvalylalanylisoleucylarginylserylalanylasparaginylisoleucyl
asparaginylleucylvalylasparaginylglutamylleucylvalylarginylglycylthreonylglycylleucyltyrosylaspar
aginylglutaminylasparaginylthreonylphenylalanylglutamylserylmethionylserylglycylleucylvalyl
tryptophylthreonylserylalanylprolylalanylserine  - Tobacco Mosaic Virus, Dahlemense Strain (1, 800 odd letters)

Floccinaucinihilipilification  - the act of estimating something as worthless

Pneumonoultramicroscopicsilicovolcanoconiosis - miners lung disease

Hepaticocholangiocholecystenterostomy - Surgical creation of a passage between the intestine, gall bladder and a hepatic duct

Honorificabilitudinitatibus - with honour, as used by Shakespeare

Philosophicopsychological - pertaining to philosophy and psychology

 Anzofate
 Bohm
 Graeme Cree