1 [noncount] : a very strong feeling of fear, dread, and shock
There was a look of horror on her face.
He saw to his horror that he couldn't escape. [=he was horrified to see that he couldn't escape]
The crowd watched in horror as the fire spread.
2 [noncount] : the quality of something that causes feelings of fear, dread, and shock : the horrible or shocking quality or character of something
His friends were shocked by the horror of his death.
the horror of war
3 : something that causes feelings of fear, dread, and shock : something that is shocking and horrible
His crimes were unspeakable horrors.
His memoirs recount the horrors of the war.
tales of horror