I don't know whether my friend Anthony Herron crafted this himself or sourced it from elsewhere, but this article I got from him via email will surely interest students of language. A related work is Richard Lederer's widely distributed essay, "English is a Crazy Language," which can be viewed here. For "Poems on the Absurdities of English" go to this site.
An overview of strange words in English is a difficult one, as there is no firm standard whereby to judge if a word has entered the language (particularly with regard to foreign words and neologisms -- newly invented words) or departed the language through disuse.
For the purposes of this article, any word which has appeared in a recognized general English dictionary published in the 20th century or later is considered a candidate.
The dictionaries included as reference sources for this article are:
• OED - The Oxford English Dictionary (any post-1900 edition)
• WNID - Webster's New International Dictionary (any post-1900 edition)
• MWCD - Merriam-Webster's Collegiate Dictionary (any post-1900 edition)
• OSPD - The Official Scrabble Players Dictionary (any post-1900 edition)
• TMD - The Macquarie Dictionary (any post-1900 edition)
• RHUD - Random House Unabridged Dictionary (any post-1900 edition)
Most people are aware that the letter y can serve as both a consonant and a vowel. However, cwm (pronounced "koom", defined as a steep-walled hollow on a hillside) is a rare case of a word using w as a vowel, as is crwth (pronounced "krooth", a type of stringed instrument). Both words are in MWCD. They derive from the Welsh use of w as a vowel. The word cwm is commonly applied to Welsh place names; cwms of glacial origin are a common feature of Welsh geography.
Arguably, however, both these examples may belong in 'Words of Foreign Origin', as they are actual words in the Welsh language which have been absorbed in the local forms of English. See 'coombe' as the south-west English equivalent of 'cwm'.
The longest word without repeating any letters
"Uncopyrightable", with fifteen letters, is the longest word in English in which no letter is used more than once.
5 vowels in a row
There is only one common word in English that has five vowels in a row: "queueing".
6 consonants in a row
The word "knightsbridge" has six consonants in a row, as does "latchstring".
5 vowels in alphabetical order
There are several words that feature all five vowels in alphabetical order, including "facetious" and "abstemious".
Strange pairs or groups of words
EWE and YOU are a pair of words with identical pronunciations that have no letters in common. Another example is the pair, EYE and I. However such word pairs are often dependent on the accent of the speaker. For instance Americans might well believe that A and EH form such a pair whereas other English speakers might not.
The most notorious group of letters in the English language, ough, can be pronounced at least nine different ways.
"UFF" tough, enough
"OW" bough, slough
"OH" though, dough
"OR" thought Pronounced "AW" in American English
"UH" thorough Pronounced "OH" in American English
"UP" hiccough variant spelling of "hiccup", though the latter form is recommended in both British and US