signalled

Signalled is the past tense and past participle of the verb signal in British English. To signal means to convey information or instructions by a gesture, sound, device, or other indicator, or to indicate the presence or occurrence of something. Signalled actions include a conductor signalling a stop, a warning beacon signalling danger, or a whistle signalling the start of a race.

Spelling and dialects vary. In American English the corresponding form is signaled (with one l). British and other Commonwealth usages typically prefer signalled and signalling, reflecting the general spelling patterns of that variety of English. Both forms are correct within their respective dialects.

Usage notes emphasize that signalled is a transitive or intransitive verb depending on construction. Examples include “The referee signalled for extra time” (transitive) and “The whistle signalled the end of play” (intransitive, with the signal itself as the subject). The term can apply to any situation where a signal is used to communicate a message, warn of danger, or indicate a state or action, across domains such as transportation, telecommunications, and safety systems.

Related terms include signal, signaling, signalization, and the noun signal, as well as domain-specific concepts like railway signals and traffic signaling. The concept of signalled thus encompasses both the act of sending a signal and the result of that signal being recognized or displayed.