# red flag

idiom

Source: https://englishreference.com/idiom/red-flag
Updated: 2026-08-10

## Meaning

Something that will enrage a particular person; a red rag.

## Examples

- His rude behavior is a major red flag.
- She noticed a red flag when he refused to talk about his past, so she decided to be careful.
- Ignoring every red flag during the initial negotiations, the investors proceeded with the merger, only to discover the company was deeply in debt.

---

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.