Military aid to the civil power refers to the involvement of the military in maintaining law and order in certain situations. There are several synonyms that can be used for this term, such as martial law, military intervention, assistance from the armed forces, and deployment of troops. These terms are often used in times of emergency or crisis, such as during natural disasters or mass protests. Military aid to the civil power can also be used in situations where the police force is not equipped to handle the situation or when there is a threat to national security. Overall, these synonyms emphasize the role of the military in supporting the civil authorities in maintaining peace and order.