shrewd
Smart in a sharp, practical way about people and situations.
Shrewd means having sharp, practical judgment, especially about people and situations. A shrewd person notices details others miss and makes smart decisions based on what they observe. When a detective is described as shrewd, it means she picks up on small clues and figures out what really happened.
Being shrewd often involves understanding people's motivations. A shrewd negotiator knows when someone is bluffing. A shrewd shopper spots the best deals and avoids tricks stores use to make people spend more money. The word suggests street-smart intelligence: the ability to read situations and make wise choices based on real-world experience, not only what you learn from books.
Shrewd carries a hint of cleverness and sometimes even cunning. A shrewd businessperson might be respected for their ability to see opportunities others overlook. In classic stories like Charlotte's Web, Templeton the rat is shrewd: he looks out for himself and always seems to know what's really going on.