Read the text and answer questions 13 to 15

    Yesterday night was the night of the fair, the following day was holiday. The children at Tim's school were really excited. They ran down the path out of school as fast as they could. Tim ran all the way home, and changed into his jeans and sneakers. He ate his dinner quickly, and sat at the window waiting for his dad to come. He couldn't wait for six o'clock when the fair would begin. He had been saving his pocket money for weeks.

    When Tim and his family arrived at the fair, it had just opened. Already there were crowds of people swarming around food stalls, displays and dozens of rides. "Can I buy some chips and a drink?" asked Tim.

    "Okay" sad Tim's dad. "But hang on tightly to your wallet. There are a lot of people around." "I'll be fine', said Tim impatiently.

    He found a food stall, and ordered his food. When the man brought his chips and drink, without thinking, Tim put his wallet on the counter and picked up his food and drink. When he glanced back, his wallet had vanished! Tim desperately looked around him, but it was no use. All his pocket money was gone.

(Source : Exploring Writing by Sue Garnet)

15. "When he glanced back, his wallet has vanished!" (last paragraph). The underlined word means ....