or **Sentry**, in military affairs, is a private soldier placed in some post, to watch the approach of the enemy, to prevent surprises, or to stop such as would pass without orders or discovering who they are. They are placed before the arms of all guards, and at the tents and doors of general officers, colonels of regiments, &c.

**Sentinel Perdu**, a soldier posted near an enemy, or in some dangerous position, where he is in hazard of being lost.

**Sentinel, Great and Little**, are two islands in the Eastern Seas. The first is about ten miles in circumference, and is about twenty miles from the Greater Andaman. Long. 92. 40. E. Lat. 11. 36. N. The second is about eight miles from the Little Andaman. Long. 92. 23. E. Lat. 10. 59. N.