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Word of the Day Tuesday, June 9, 2026

sentinel

/ˈsɛntɪnəl/ noun · British & US
Valid in UKValid in US
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What does sentinel mean?

noun

A person or thing that watches or guards something, especially a person who is left to guard a place or a machine that automatically stops a process if something goes wrong. A biological marker or protein that is used to detect the presence of a disease or condition.

Example

"The security guard acted as a sentinel, watching the entrance to the building."

Definition generated by AI and curated by RJS Tech Solutions LLP.

Synonyms for sentinel

Antonyms of sentinel

Rhymes with sentinel

Etymologically related