1. tool for pounding or grinding in a mortar.   indices   spatula   pestle   pigment   Hint Half-n-half Clue   2. sameness or consistency.   nutrient   matrix   refraction   uniformity   Half-n-half Clue   3. product of mass and velocity for a moving body; impetus.   transition   pachyderm   momentum   pterodactyl   Half-n-half Clue   4. observed fact or occurrence subject to scientific study.   phenomenon   suture   placebo   stratum   Half-n-half Clue   5. terminology or method of naming.   microcosm   nutrient   iota   nomenclature   Half-n-half Clue   6. terms used in a science or discipline.   respiration   isotope   vent   terminology   Half-n-half Clue   7. slope or slanting plane.   incline   serendipity   touchstone   isotope   Half-n-half Clue