愚蠢 means 'foolishness' or 'stupidity' and functions both as a noun (e.g., 'his foolishness') and an adjective (e.g., 'a foolish decision'). The character 愚 (yú) originally meant 'to be ignorant' or 'to lack wisdom', often with a connotation of moral or intellectual deficiency; 蠢 (chǔn) literally means 'to wriggle' (like insects), but in compound form it intensifies the sense of clumsy, irrational, or mindless behavior. Together, they form a strong, slightly formal or literary term — more severe than casual words like 傻 (shǎ) and less clinical than 智力障碍 (zhìlì zhàng'ài). It’s commonly used to criticize poor judgment, reckless actions, or willful ignorance, especially in serious contexts like politics, ethics, or personal responsibility.

The word carries mild-to-moderate negative weight — it’s not vulgar, but it’s sharper than neutral terms and best avoided in polite or sensitive situations. It appears frequently in written Chinese (essays, news commentary, literature) and occasionally in spoken language when expressing strong disapproval.