Uni-

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Across
  1. 3. to join together into one group
  2. 5. a horse like fabled animal that has one horn growing out of the middle of its forehead
  3. 6. having only one cell
  4. 7. an instance of saying the same words or sounds at the same time; a group that sounds like one
  5. 9. one sided
Down
  1. 1. moving in only one direction
  2. 2. a one wheeled vehicle on which the rider sits and pedals
  3. 4. one of a kind; unusual
  4. 7. one group
  5. 8. a one piece leotard and tights combination