a book (or manuscript) consisting of large sheets of paper folded in the middle to make two leaves or four pages; "the first folio of Shakespeare's plays"
(Greek mythology) a beautiful princess loved by Cupid who visited her at night and told her she must not try to see him; became the personification of the soul
a natural and unavoidable catastrophe that interrupts the expected course of events; "he discovered that his house was not insured against acts of God"