蠢 (chǔn) is a direct, somewhat informal word for 'stupid/foolish,' often used for a person's actions or ideas. Compared to nearby synonyms: 笨 (bèn) emphasizes slow-wittedness or clumsiness, 傻 (shǎ) implies naivety or being easily fooled, 呆 (dāi) suggests a blank, expressionless dullness, and 愚蠢 (yúchǔn) is the more formal, written equivalent.