1. substance formed by decay of organic material.   congruence   humus   homeostasis   clavicle   Hint Half-n-half Clue   2. mode of formation or origin.   homeostasis   genesis   aureole   discrepancy   Half-n-half Clue   3. correspondence or harmonious relation.   fauna   friction   congruence   cartographer   Half-n-half Clue   4. disproportion or lack of balance.   dissertation   conjecture   imbalance   galaxy   Half-n-half Clue   5. tooth of a wheel.   cog   floe   eccentricity   imbalance   Half-n-half Clue   6. ability to produce desired effect.   catalyst   dissection   dichotomy   efficacy   Half-n-half Clue   7. botanical garden where trees are studied and exhibited.   arboretum   atavism   eccentricity   correlation   Half-n-half Clue