1. optimum   best or most favorable.   of many forms.   caustic or sharp in taste or smell.   pertaining to a semi-fluid gluey consistency.   Hint Half-n-half Clue   2. synthetic   artificial or produced by synthesis.   pertaining to the lungs.   pertaining to earthquakes.   pertaining to motion.   Half-n-half Clue   3. rigid   pertaining to a semi-fluid gluey consistency.   inflexible or strict.   pertaining to space.   pertaining to disease.   Half-n-half Clue   4. turbid   muddy or not clear.   pertaining to the earth.   opalescent or displaying rainbow-like colors.   pertaining to the sense of touch.   Half-n-half Clue   5. tactile   pertaining to heat.   pertaining to the earth.   pertaining to a semi-fluid sticky consistency.   pertaining to the sense of touch.   Half-n-half Clue   6. stellar   exact or accurate.   pertaining to the stars.   pertaining to the sense of touch.   pertaining to a semi-fluid sticky consistency.   Half-n-half Clue   7. osseous   at rest or in equilibrium.   opalescent or displaying rainbow-like colors.   bony or having bones.   for a short time or momentary.   Half-n-half Clue