Cool words - http://www.reddit.com/r/Showerthoughts/comments/2irpuq/eclipse_is_probably_the_longest_word_in_the/

coolwords.coffee

# Get your word list:
# curl 'http://www-01.sil.org/linguistics/wordlists/english/wordlist/wordsEn.txt' -O

fs = require 'fs'

words = for word in fs.readFileSync('wordsEn.txt', 'utf8').split '\n' when word != ''
  if word[word.length - 1] is '\r'
    word[...word.length - 1]
  else
    word

#console.log words.length

w = {}
w[word] = true for word in words
w['i'] = true # Missing for some reason.

longest = ''
for word in words
  w2 = word
  cool = true
  while word.length > 0 and cool
    cool = false unless w[word]
    word = word[1...word.length - 1]

  if cool
    if w2.length > longest.length
      longest = w2
    console.log w2 if w2.length >= 7


console.log 'longest', longest

gistfile1.txt

8 letter words:

balinese
blessers
braiders
dopiness
drabbets
gaminess
lashings
methanes
pleasers
relaters
ropiness
washings


7 letter words:

ashamed
ashiest
borated
borates
bovines
bowings
busings
dosages
eclipse
escaped
escapee
escaper
escapes
estated
estates
flyings
lawings
lowings
musings
pirated
pirates
prearms
rowings
salient
scraped
scraper
scrapes
scrawls
scrawly
scrimps
scrimpy
sewings
sheathe
sheaths
striped
striper
stripes