paper covers


booklet a very short book with paper covers that usually contains information on one particular subject
brochure a thin book with paper covers that gives information on something you may want to buy or advertises something:
pamphlet a very thin book with paper covers, in which someone writes about their opinions about something, or gives information about something:
(Longman DOCE 5th Ed.)

Why is "cover" in plural here?

Thank you
  • Egmont

    Senior Member
    English - U.S.
    Because a pamphlet, or any other type of bound book, has two covers: a front cover and a back cover. They are thought of and referred to as separate covers even if they are formed from a single sheet of paper folded in the middle.