Definitions

1. noun

a person or thing that watches or guards something, especially to give warning of danger

“The lighthouse stood as a sentinel, warning ships of the rocky coastline.”

2. noun

a type of plant that grows in a particular situation, such as a tree that grows on a cliff

“The sentinel oak tree stood tall on the hillside, its roots digging deep into the rocky ground.”

3. noun

a type of animal, especially a bird, that serves as a warning or indicator of something

“The sentinel bird perched on the branch, its bright plumage serving as a warning signal to potential predators.”

4. verb

to act as a guardian or protector of something

“The park ranger sentinel-ed the forest, making sure that no one trespassed on the protected land.”