1. pertaining to extracting and processing metals.   rarefied   opalescent   metallurgical   osseous   Hint Half-n-half Clue   2. pertaining to the internal body organs.   lunar   visceral   viscid   repellent   Half-n-half Clue   3. pertaining to the stars.   pulmonary   kinetic   sidereal   metallurgical   Half-n-half Clue   4. haphazard or without definite pattern.   multiform   random   nocturnal   schematic   Half-n-half Clue   5. putrid or causing putrefaction.   permeable   mnemonic   septic   redundant   Half-n-half Clue   6. pertaining to memory or memory-aid.   tautological   mnemonic   septic   rarefied   Half-n-half Clue   7. unnecessarily repetitious.   transient   tautological   nocturnal   optimum   Half-n-half Clue