1. pterodactyl   flying reptile now extinct.   dependant or small heavenly body revolving round large one.   center of turbulence or whirling motion.   navigational instrument for angular measurements.   Hint Half-n-half Clue   2. projectile   representation on a miniature scale.   harmless substance given as dummy medicine.   size or extent.   missile or shell.   Half-n-half Clue   3. penumbra   discovery by accident.   product of mass and velocity for a moving body; impetus.   breathing.   partly lighted shadow.   Half-n-half Clue   4. virus   poisonous element that communicates infection.   animal or plant living in or on another; sycophant.   incompatibility or lack of uniformity.   substance that helps propel or push forward.   Half-n-half Clue   5. insomnia   navigational instrument for angular measurements.   terms used in a science or discipline.   slope or slanting plane.   sleeplessness.   Half-n-half Clue   6. trough   incompatibility or lack of uniformity.   discovery by accident.   supporting bar in framework or pompous walk.   lowest point in wave; shallow receptacle.   Half-n-half Clue   7. symbiosis   dependence (of organisms) that is mutually beneficial.   natural environment; nutrient setting for microorganism.   different form of an element.   representation on a miniature scale.   Half-n-half Clue