Translation guide
A warning sign or indicator of a problem, danger, or undesirable trait, often used in relationships, business, or safety contexts.
To describe a behavior or trait that signals potential problems in a person or relationship.
Literally 'danger signal', this is the most direct and common translation for 'red flag' in the sense of a warning sign in relationships or situations.
His attitude is a red flag.
Loanword from English, commonly used in casual conversation, especially among younger people or in online contexts.
Isn't that a red flag?
Means 'a sign to be wary of', slightly more formal and explanatory.
That behavior is a red flag.
To refer to any sign that something is wrong or risky, such as in business, health, or safety.
To refer to a physical red-colored flag, such as in sports or signaling.
Standard term for a red flag as an object.
The referee raised a red flag.
危険信号 is the standard Japanese term and is understood by all ages. レッドフラッグ is a loanword popular among younger generations and in online communities, but may sound casual or trendy.
That person's lies are a red flag.
That's a red flag.
Red flags are appearing in the economy.