What is the difference between sympathy and empathy? Is a collaborator the same thing as a collaborationist? What about contemporary and contemporaneous? Is it acceptable to say "equally as good"? Should it be demur or demure? Ketchup or Catchup? Which verb number follows "each"? The complexities of the English language can be daunting for even the most fluent speakers. Almost anyone engaged in formal writing - letters, reports, memos, school essays - will sometimes need to consult a usage guide for advice on matters such as these.