What does warning mean?
Warning names an act of caution and the information communicated through it. As a noun, it can refer to a spoken or written caution, a warning sign or signal, or an indication that danger or difficulty may be present. As a verb, warning means to alert someone to a risk, error, or undesirable outcome, often with advice about how to respond. The word commonly carries a serious but protective connotation: it communicates that attention is needed without necessarily claiming that harm is certain. In British and American English, it appears in everyday conversation, official announcements, legal and safety contexts, and technical descriptions. Warning can also function attributively, especially in expressions such as warning sign, warning label, and warning device. Its usefulness lies in connecting information with practical caution: it helps people recognize a problem before it becomes harder to manage.
A statement, sign, or other indication that alerts people to possible danger, error, or misconduct.
"The label contains a warning about possible allergic reactions."
Warning is commonly countable, and the plural warnings is standard. The word can denote a formal notice, a caution from an authority, or a visible safety signal.
To alert or caution someone about a possible danger, error, or problem.
"The report warns that temperatures may rise above forty degrees."
As a verb, warning frequently takes a person as its object or uses a construction such as warn someone about something or warn someone not to do something.
Serving as a warning or indicating a potential problem.
"A warning light came on when the machine malfunctioned."
The adjective is chiefly used attributively, especially with words such as sign, label, device, and light.
The standard plural of the noun is warnings, as in officials issued several warnings.
"The repeated warnings about the storm were widely broadcast."
A warning is often the difference between a close call and a disaster: it turns uncertain danger into information people can act on.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does warning come from?
The English noun and verb descend from Old English wiernan, meaning to warn, caution, or admonish. This belonged to an older Germanic vocabulary associated with watchfulness and keeping oneself alert. Related developments in Germanic languages produced words such as warrant, guarantee, and wary, all reflecting the broader idea of protection, assurance, or caution.
Related word forms
How warning is actually used
As a noun, warning is commonly countable and is used for both spoken or written cautions and visible signals, such as warning signs. As a verb, it often takes an object or an indirect object: warning people about a risk or warning someone not to proceed. The attributive adjective is especially common in labels and signs, as in warning sign and warning device.