1. of exterior curvature or bulging outwards.   fundamental   cerebral   astronomical   convex   Hint Half-n-half Clue   2. characteristic of a genus; not specific.   inevitable   dorsal   concave   generic   Half-n-half Clue   3. having indigestion.   derivative   dyspeptic   astral   empirical   Half-n-half Clue   4. boiling or enthusiastic.   combustible   ebullient   corrosive   impermeable   Half-n-half Clue   5. impenetrable or unpassable.   abstract   cosmic   impervious   immune   Half-n-half Clue   6. arranged in gradations (e.g., of difficulty).   empirical   dyspeptic   graduated   ebullient   Half-n-half Clue   7. causing compression or contraction.   aromatic   discrete   hybrid   astringent   Half-n-half Clue