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.

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

Conceptual illustration: Two adults stand in a room; one is clearly dominant, standing tall and pointing, while the other is looking down, visibly excluded from the decision-making process. The lighting is dramatic, highlighting the power imbalance between the two and the isolation of the second person.

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

Discover more words on Wordspun