疑惑 is a noun meaning 'doubt' or 'suspicion' — a feeling of uncertainty about the truth, reliability, or intention of something or someone. The first character 疑 (yí) means 'to doubt' or 'to suspect', often implying hesitation or lack of conviction; the second character 惑 (huò) means 'to confuse' or 'to perplex', suggesting mental uncertainty or bewilderment. Together, they form a compound that emphasizes an internal state of questioning and confusion, rather than active accusation.

This word is commonly used in formal writing, academic discussions, and everyday speech when expressing intellectual or emotional uncertainty — for example, about someone’s motives, a surprising event, or unclear instructions. It’s more neutral and introspective than words like 怀疑 (to suspect with negative connotation) and less intense than 迷惑 (which stresses confusion over cause). 疑惑 can function as the subject or object of a sentence and often appears after verbs like 产生 (to arise), 消除 (to dispel), or 表达 (to express).