keen mind

• sharpFine-edged, or astute
• intellectMental reasoning capacity
• brilliantIntensely bright or gifted
• astuteMentally sharp, discerning
• cleverShowing mental quickness

wit · incisive · perceptive · quick · razor · analytical · shrewd · bright · agile · penetrating · discerning · alert · cunning · genius · savvy · nimble · insightful · brainy

• mental agilityquick wit, mental flexibility, sharp mind, quick-witted, sharp-witted
• mental claritymental clarity, lucidity, clear thinking, clear head, clear-headedness