(s)crisp, sharp(of something seen or heard) clearly defined“a sharp photographic image”, “the sharp crack of a twig”, “the crisp snap of dry leaves underfoot”
(s)acute, discriminating, incisive, keen, knifelike, penetrating, penetrative, piercing, sharphaving or demonstrating ability to recognize or draw fine distinctions“an acute observer of politics and politicians”, “incisive comments”, “icy knifelike reasoning”, “as sharp and incisive as the stroke of a fang”, “penetrating insight”, “frequent penetrative observations”
(s)astute, sharp, shrewdmarked by practical hardheaded intelligence“a smart businessman”, “an astute tenant always reads the small print in a lease”, “he was too shrewd to go along with them on a road that could lead only to their overthrow”
(s)abrupt, precipitous, sharpdangerously steep“an abrupt canyon”, “the precipitous rapids of the upper river”, “the precipitous hills of Chinese paintings”, “a sharp drop”
(r)sharply, sharp, acutelychanging suddenly in direction and degree“the road twists sharply after the light”, “turn sharp left here”, “the visor was acutely peaked”, “her shoes had acutely pointed toes”