The word 慎入 is formed by combining the character 慎 (shèn), meaning "cautious" or "prudent", with the character 入 (rù), meaning "to enter". In this construction, 慎 functions as an adverb modifying the verb 入, resulting in a phrase that literally means "enter cautiously" or "caution: entry", used to warn of content that may be disturbing or unsuitable.