# alertness

/əˈɫɝtnəs/ (US) · /ɐlˈɜːtnəs/ (UK) · CEFR B2 · Noun

Source: https://englishreference.com/word/alertness
Updated: 2026-05-28

## Definition

the state of being awake and ready to notice things. It means you are paying close attention to what is happening around you.

For teachers: the state of being awake and mentally alert; the quality of being quick to notice or respond to something. Often used in medical or safety contexts to describe a person's level of consciousness.

## Examples

- The driver's alertness is very important on the highway.
- The nurse monitored the patient's alertness to ensure the medication was not causing any drowsiness.
- Maintaining high levels of alertness during the final hours of the shift requires a combination of physical stamina and mental discipline to avoid critical errors.

---

From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.