The dictionary.com definitions for terror:
1.
intense, sharp, overmastering fear: to be frantic with terror.
2.
an instance or cause of intense fear or anxiety; quality of causing terror: to be a terror to evildoers.
3.
any period of frightful violence or bloodshed likened to the Reign of Terror in France.
4.
violence or threats of violence used for intimidation or coercion; terrorism.
5.
Informal. a person or thing that is especially annoying or unpleasant.
I believe terror is the situaion where you are scared or in fear for a more extended period of time. In my film I will have to try and cause the viewer to be on this situation of terror throughout.