1. implied but not expressed.   implicit   cognitive   feasible   fundamental   Hint Half-n-half Clue   2. produced by fire or volcanic action.   dynamic   convex   igneous   astronomical   Half-n-half Clue   3. based on experiment, not theory.   eccentric   empirical   aromatic   convex   Half-n-half Clue   4. pertaining to the brain.   inevitable   ebullient   concurrent   cerebral   Half-n-half Clue   5. having common center.   deducible   concentric   congruent   concave   Half-n-half Clue   6. pertaining to mental processes or knowing.   concave   cognitive   cosmic   immune   Half-n-half Clue   7. shaped like an oval; ambiguous or baffling.   impervious   hazardous   hybrid   elliptical   Half-n-half Clue