Under guard means to be protected or watched over by a security team or law enforcement agency. There are several synonyms for this term, including being under surveillance or monitored by security personnel. Other related words include being detained or in custody, restrained, or under close observation. These words all convey a sense of being monitored or restricted in some way, and are frequently used in legal or security situations. Other related terms may include protective custody, secure confinement, or guarded status. Ultimately, all of these words reflect the importance of being protected and monitored in order to maintain public safety and security.