Red Flag
noun /rɛd flæɡ/ — A warning sign of potential danger or serious concern
Definition
A warning sign — a behaviour, statement, or pattern that indicates serious concern about a person, relationship, or situation. Red flags demand attention; they are the signals that something important is wrong.
Beyond the definition
Red flag is the word for the moment you know something is wrong before you can articulate why. The metaphor is exact: a red flag is a signal to stop, to not proceed, to take seriously what your gut is telling you.
Origin & history
Originally nautical: ships flew red flags to signal danger or that they were not to be approached. In general usage for centuries; adopted into modern dating vocabulary in the 2010s through social media.
Example sentences
Illustrative sentences for learning, not verified community posts or sourced quotations.
He made jokes about her intelligence on the first date. Red flag.
The biggest red flag is when someone tells you who they are and you decide not to believe them.
Sometimes red flags are only visible in retrospect. Sometimes they're screaming at you in real time.
How to use it
This entry uses a noun. Follow the examples for articles and singular or plural forms; not every noun takes “a” or “an.”
Choose “Red Flag” when the meaning fits your context: A warning sign — a behaviour, statement, or pattern that indicates serious concern about a person, relationship, or situation. Red flags demand attention; they are the signals that something important is wrong.
Synonyms
warning sign, danger signal, concern, alarm bell
Antonyms
green flag, positive sign, reassurance
Related words
Red Flag vs deal-breaker
A red flag is an early warning sign that something might be problematic. A deal-breaker is a specific condition that makes continuing a relationship impossible.
Word in the Wild
See how this word appears in life, language and stories.
Illustrative sentences and imagined stories for learning — not verified sightings, interviews, or sourced quotations.
Fictional scene
Power Imbalance in Decision Room
Two adults stand in a room; one is clearly dominant while the other looks down, excluded from decisions.
The exclusion and clear inequality serve as a serious warning sign. A red flag is this pattern of behavior that indicates a deeper concern for the health of a relationship or the safety of a situation, demanding immediate attention.
Image credit: Wordspun · AI-generated conceptual illustration
Questions about this word
What does "Red Flag" mean?
Red Flag is noun meaning: A warning sign of potential danger or serious concern. A warning sign — a behaviour, statement, or pattern that indicates serious concern about a person, relationship, or situation. Red flags demand attention; they are the signals that something important is wrong.
Where does the word "Red Flag" come from?
Originally nautical: ships flew red flags to signal danger or that they were not to be approached. In general usage for centuries; adopted into modern dating vocabulary in the 2010s through social media.