Learner's definition of TERROR
1 : a very strong feeling of fear
The sound of guns being fired fills me with terror.
There was a look of (sheer) terror on her face.
Many civilians fled in terror.
They lived in terror of being discovered. = They lived in terror that they would be discovered.
Until recently, the mere mention of the disease struck terror in (the hearts of) people.
2 : something that causes very strong feelings of fear : something that is terrifying
3 [noncount] : violence that is committed by a person, group, or government in order to frighten people and achieve a political goal
a regime that rules by terror
bombings and other acts of terror
These people have been living with terror and the threat of terror for many years.
a war on terror [=terrorism]
a campaign of terror against ethnic minority groups
4 [count], informal : a child who behaves very badly
hold no terrororhold no terrors
◊ If something holds no terror/terrors for you, you are not afraid of it.