1. shelter, screen, shield; garrison, fortify. Defend, guard, preserve, protect all mean to keep safe. To defend is to strive to keep safe by resisting attack: to defend one's country. To guard is to watch over in order to keep safe: to guard a camp. To preserve is to keep safe in the midst of danger, either in a single instance or continuously: to preserve a spirit of conciliation. To protect is to keep safe by interposing a shield or barrier: to protect books by means of heavy paper covers. 2. vindicate.