Get Your Head Around These! 2

15 Points Per Correct Answer - No time limit  

1. I begin and end with U-N-D. A subterranean word. Can you deduce me? Answer: (One Word)

2. The more I am, the less you see Strange result - What can I be? Answer: (One Word)

3. I can only be kept if I’m given first. This does not work if the order's reversed. I am a ______? (Read the hint) Answer: (One Word (Hint: Don't break it))

4. At both extremes of the day, I'm the same distance away. I look the same from each end. High time you solved me my friend. Answer: (One Word)

5. Seen in one form at night, and another by day. By night I'm at flight, by day used for play. Answer: (One Word or Two Words)