Red flag is an idiom that may be used as a noun or a verb, in which case the expression is hyphenated. An idiom is a word, group of words or phrase, or phrasal verbs that have a figurative meaning that is not easily deduced from its literal definition. These figures of speech often use descriptive imagery, common idioms are words and phrases used in the English language in order to convey a concise idea, and are often colloquialisms or descriptors that are spoken or are considered informal or conversational. English idioms can illustrate emotion more quickly than a phrase or expression that has a literal meaning, even when the etymology or origin of the idiomatic expression is lost. An idiom is a metaphorical figure of speech, and it is understood that it is not a use of literal language. Figures of speech have definitions and connotations that go beyond the literal meaning of the words. Mastery of the turn of phrase of an idiom or other parts of speech is essential for the English learner. Many English as a Second Language students do not understand idiomatic expressions that native speakers understand such as in a blue moon, spill the beans, let the cat out of the bag, chin up, eye to eye, barking up the wrong tree, bite the bullet, beat a dead horse, hit the nail on the head, kicked the bucket, blow off steam, jump on the bandwagon, piece of cake, hit the sack, and raining cats and dogs, as they attempt to translate them word for word, which yields only the literal meaning. In addition to learning vocabulary and grammar, one must understand the phrasing of the figurative language of idiomatic phrases in order to know English like a native speaker. It is possible to memorize a list of idioms, but it may be easier to pay attention to the use of idioms in everyday speech, where peculiar imagery will tell you that the expressions should not be taken literally. We will examine the meaning of the idiomatic phrase red flag, where it came from, and some examples of its use in sentences.
The noun red flag, when used as an idiom, means a warning, a clue that there may be a problem, a sign of danger. The verb red-flag means to identify something as a sign of danger, to label something as a warning. Related words are red-flags, red-flagged, red-flagging. Note that the verb form takes a hyphen. A red flag was used in the 1600s to signal that an army was ready to go into battle. By the 1700s, red flag came into use as an idiom to mean a warning sign. Literal, physical red flags are used as a sign of warning in many circumstances. Red flags are used in sports, as a sign of wildfire hazard, as a train signal, as a rank of terrorist threat, and in many, many other ways. In all cases, the red flag is a warning of danger.
It’s the third year Handy has tried to push a “red-flag” bill — or legislation that would enable a family member or someone from law enforcement to request a court strip a firearm from a person in crisis, either in danger to themselves or others. (The Deseret News)
Delta, American, and United just suspended all China flights, a red flag as the unprecedented coronavirus wreaks havoc on the airline industry (Business Insider)
He alleged that Low with the help of other unauthorised third parties, had made 20 transactions to regularise the accounts totalling RM12 million through several local and foreign remittances of funds and that the accounts had been ‘red-flagged’ by Bank Negara Malaysia (BNM). (The Borneo Post)