Uni-

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Across
  1. 2. a one-piece leotard
  2. 3. one of a kind; unusual
  3. 4. one group
  4. 6. to join together into one group
  5. 7. having only one cell
Down
  1. 1. move in one direction
  2. 2. a one-wheeled vehicle
  3. 3. saying things at the same time
  4. 4. a horse-like fabled animal
  5. 5. one sided