# sentinel

> English word · Noun · IPA /ˈsɛn.tɪ.nəl/ · frequency rank #17,027

## Definitions
1. A sentry, watch, or guard.
2. A private soldier.
3. A unique value recognised by a computer program for processing in a special way, or marking the end of a set of data.
4. A sentinel crab.
5. A sign of a health risk (e.g. a disease, an adverse effect).

## Etymology
1570s, from Middle French sentinelle, from Old Italian sentinella (perhaps via a notion of "perceive, watch", compare Italian sentire (“to feel, hear, smell”)), from Latin sentiō (“feel, perceive by the senses”). See sense, sentient.

## Common misspellings (12)
`esntinel`, `senitnel`, `senntinel`, `sentienl`, `sentinell`, `sentinle`, `sentinnel`, `sentniel`, `senttinel`, `setninel`, `snetinel`, `ssentinel`

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-05-06.
Canonical page: https://plainspell.com/en/word/sentinel