Prefix Uni- having or consisting of only one

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Across
  1. 1. being one
  2. 2. a one-piece garment
  3. 3. altogether as one
  4. 4. a horse with one horn
  5. 6. one single cell
Down
  1. 1. wearing a specific thing to school every day
  2. 2. a vehicle consisting of only one wheel
  3. 4. a single legislative
  4. 5. all matter in space grouped as one