| apprehensive(adjective, cool, crack, significant, intelligent) |
| argute(sharp, smart, intelligent, clever, astute) |
| astucious(sharp, smart, intelligent, clever, astute) |
| attentive(reasonable, thoughtful, serious, perceptive, observant) |
| au fait(expression, adjective, familiar, informed, well-informed) |
| brainier |
| brainiest |
| cagey(adjective, good, smooth, keen, sharp) |
| cerebric |
| clean(expert, skilled, capable, skillful, adroit) |
| clear-headed(adjective, intelligence wisdom) |
| clearheaded |
| cogent(adjective, intelligent) |
| cogitative(adjective, reasonable, keen, deep, rational) |
| competent(adjective, good, cool, smart, bright) |
| conscious(adjective, understanding, cool, keen, sharp) |
| contemplative(adjective, reasonable, keen, deep, rational) |
| conusant(adjective, knowledge, experience, skill, expert) |
| conversant(adjective, understanding, cool, significant, familiar) |
| cool(adjective, smooth, smart, sensible, significant) |