Acumen (noun) = it indicates a clarity of thought,, sharpness of perception, keenness of mind, precise insightfulness. Today's word seems to be an orphan but it is related to the family of acuminate "to sharpen, shape into a point," whose noun is "acumination." We see a clearer resemblance in the adjective of today's word. Today's word is more precise and focused than "smart" or "intelligent;" "Marjorie is not only intelligent and well-educated; her acumen leads us through the murkiest problems quickly and surely." In this sentence, using the focused term serves to emphasize (the absence of ) intelligence, "How much acumen does it take to avoid sticking your tongue to a frozen pipe the second time?"
Acuminous (adj)
Insightful (adj):able to understand or showing that you understand what a siutuation or person is really like. An insightful/perceptive analysis.
Keen (adj) = eager to work/learn: The kids in my class are very keen.
Knowledgeable (adj): knowing a lot. He is very knowledgeable about wines
Perceptive (adj): Someone who is perceptive notices things quickly and understands situations, people’s feelings. A perceptive young woman. You are right. That’s very perceptive of you. Those are highly perceptive arguments.
Savvy (noun and adj): practical knowledge and ability (He has obviously got a lot of political savvy); someone who is clever and knows how to deal with situation successfully (savvy customers).
Source: Your Dictionary; Longman's