1. diverse or mixed.   Hint First letter clue   2. pertaining to the back (of an animal).   First letter clue   3. periodic shedding (of leaves).   First letter clue   4. leading to absence of pain.   First letter clue   5. produced by fire or volcanic action.   First letter clue   6. inferred by reasoning; derived as conclusions.   First letter clue   7. impervious or unpassable.   First letter clue