require 'wordsdotdat'

a = WordsDotDat.words

a.sample
#=> "cheeseflower" 

a.include? 'laugh'
#=> true

%w(stop stopping run cry quick quickly furtive furtively fertive nonce)\
  .map {|x| a.include? x}
#=> [true, true, true, true, true, false, true, false, false, true] 

a.include? 'frt'
#=> false