The "willing suspension of disbelief" is defined as the following:
The temporary acceptance as believable of events or characters that would ordinarily be seen as incredible. This is usually to allow an audience to appreciate works of literature or drama that are exploring unusual ideas.
This term refers to actions or happenings which happen in literature, or other narratives (such as film), in which the reader decides to forgo previous thought on an idea and replace it with a willingness to accept the action as simply being what it is for the duration of the work.
This allows readers to accept ideas of an author as acceptable based upon the fact that they understand the the work is a piece of fiction. This allows a reader to more fully enjoy the work, by allowing the reader to "let go", given all concern for reality is temporarily released. This being said, the imagery and actions associated must be considered by the reader as believable.