(countable) Specific instance of being intensely terrified.
(uncountable) The action or quality of causing dread; terribleness, especially such qualities in narrative fiction.
(countable) Something or someone that causes such fear.
Esimerkit
The terrors with which I was seized[...]were extreme.
1921, Edith Birkhead, The tale of terror: a study of the Gothic romance
The terrors of the storm
A chap named Eleazir Kendrick and I had chummed in together the summer afore and built a fish-weir and shanty at Setuckit Point, down Orham way. For a spell we done pretty well. Then there came a reg'lar terror of a sou'wester same as you don't get one summer in a thousand, and blowed the shanty flat and ripped about half of the weir poles out of the sand.