The Chinese word 痴呆 (chīdāi), meaning "dementia" or "stupidity", is a compound formed by combining two semantically related characters: 痴 (chī), which conveys foolishness, infatuation, or a deranged state of mind, and 呆 (dāi), which signifies dullness, blankness, or a sluggish, vacant expression. Together, they create a synergistic meaning where 痴 emphasizes the irrational or mentally unsound aspect, and 呆 emphasizes the sluggish, unresponsive, or vacant behavioral component, resulting in a term that vividly describes a severe decline in cognitive function and alertness, commonly used in both medical and colloquial contexts.