1. To fill with fear; alarm.
2. To drive or force by arousing fear: The suspect was frightened into confessing.

Synonyms: These verbs mean to cause a person to experience fear. Frighten and the less formal scare are the most widely applicable: "The Count's mysterious warning frightened me at the time" (Bram Stoker). The angry dog scared the small child.
Alarm implies the often sudden onset of apprehension: Her sudden weight loss alarmed her doctor.
Terrify implies overwhelming, often paralyzing fear: "It is the coming of death that terrifies me" (Oscar Wilde).
Terrorize implies intimidation and sometimes suggests deliberate coercion: "The decent citizen was terrorized into paying public blackmail" (Arthur Conan Doyle).
Startle suggests a momentary shock that may cause a sudden, involuntary movement of the body: The clap of thunder startled us.
Panic implies sudden frantic fear that often impairs self-control and rationality: The realistic radio drama panicked the listeners who tuned in after it had begun.