Synonyms:
* Dread: A feeling of intense fear or apprehension.
* Horror: Intense fear and disgust.
* Panic: Sudden overwhelming fear that causes irrational behavior.
* Fear: A natural human response to danger or threat.
* Fright: A sudden feeling of fear.
* Alarm: A feeling of sudden and intense fear.
* Trepidation: A feeling of fear or anxiety about something that may happen.
* Apprehension: A feeling of anxiety or fear that something bad might happen.
* Dismay: A feeling of disappointment or despair.
* Agony: Intense physical or mental pain.
* Anguish: Severe mental or emotional suffering.
Related concepts:
* Panic attack: A sudden episode of intense fear that includes physical symptoms like a racing heart, shortness of breath, and dizziness.
* Trauma: A deeply distressing or disturbing experience.
* Post-traumatic stress disorder (PTSD): A mental health condition triggered by a terrifying event.
* Nightmare: A bad dream that causes fear and anxiety.
* Phobia: An intense and irrational fear of a specific object or situation.
The best word to use depends on the context and the specific emotion you want to describe.