Which word describes someone who is clever or cunning?

The word "shrewd" is used to describe someone who possesses sharp intelligence and keen insight, often using their cleverness to understand situations and manipulate them to their advantage. A shrewd person can assess complex scenarios and make astute decisions, which may include strategies that may not be immediately obvious to others. This term captures the sense of cunning and resourcefulness that is typically associated with a person who is both wise and strategic in their thinking.

The other options have meanings that do not align with the concept of cleverness or cunning. "Shrill" refers to a high-pitched and piercing sound, while "slur" pertains to a derogatory remark or a way of speaking unclearly, neither of which implies cleverness. "Squalid" describes a state of extreme filth or misery, focusing on conditions rather than intellectual qualities. Thus, "shrewd" stands out as the word most accurately reflecting cleverness and cunning.