1. two-year long or every two years.   Hint First letter clue   2. impervious or unpassable.   First letter clue   3. cold like ice.   First letter clue   4. uncertain or not fixed   First letter clue   5. pertaining to the stars or spiritual.   First letter clue   6. that corrodes or burns; biting or sarcastic.   First letter clue   7. cancer-causing.   First letter clue