The word 警告 is formed by combining two characters, each contributing its core meaning to create a new, unified concept. The first character, 警 (jǐng), carries the inherent idea of alertness, caution, or a state of vigilance, much like a guard being on watch. The second character, 告 (gào), means to tell, inform, or notify someone of something. When placed together, their meanings fuse into the action of urgently informing or notifying someone with the specific purpose of putting them on alert, thus forming the complete concept of "to warn" or "a warning".