# sentinel

Pronunciation: say "SEN-ti-nuhl" /ˈsɛn.tɪ.nəl/

## Noun

1. A guard posted to keep watch; a sentry.
   - Simple: A person who stands guard and keeps watch.
   - _Two sentinels stood at the palace gates, rifles on their shoulders._
   - _The camp posted a sentinel on the ridge to warn of anyone approaching._
2. In medicine and epidemiology, used before a noun for something that signals a health risk, such as a disease or an adverse effect.
   - Simple: Used before a word to describe something that warns of a health danger, like a disease.
   - _Health officials keep flocks of sentinel chickens to detect mosquito-borne viruses early._
   - _A cluster of rare cancers among factory workers can be a sentinel event pointing to a workplace hazard._

## Noun

3. A private soldier; a soldier of the lowest rank. *(obsolete)*
   - Simple: An ordinary soldier who is not an officer.

## Other meanings

- (verb) To watch over a place or thing as a guard does.
- (noun) A unique value that a computer program recognizes and handles in a special way, or that marks the end of a set of data.
- (verb) To provide a place with a guard or guards.
- (noun) Short for sentinel crab: a crab from the Indian or Pacific Ocean with eyes on very long stalks, living on muddy shores.

## Origin

Recorded from the 1570s, from Middle French sentinelle, from Old Italian sentinella (perhaps through the idea of "perceive, watch"; compare Italian sentire, "to feel, hear, smell"), probably from Latin sentiō ("to feel, perceive by the senses"). It is probably related to sense and sentient.

Source: DictionaryAI, https://dictionaryai.com/define/sentinel (written from Wiktionary data, CC BY-SA 4.0: https://creativecommons.org/licenses/by-sa/4.0/).