• (of a person or mental process) intelligently analytical and clear-thinking

Synonyms: penetrating, acute, sharp, sharp-witted, razor-sharp, keen, rapier-like, astute, shrewd, trenchant, piercing, perceptive, insightful, percipient, perspicacious, discerning, analytical, intelligent, canny, clever, smart, quick

• (of an action) quick and direct