knoll

A knoll is a small hill or mound of earth, which makes a shady knoll a perfect spot for a summer picnic.

The word knoll is associated with the tragic assassination of President John F. Kennedy, who was shot in Dallas just as his motorcade passed a grassy knoll. At first people thought that was where the shots had come from, but it was later determined that the assassin had fired from a nearby building instead. The "grassy knoll” became symbolic of a theory that others had participated in the assassination, and the term has become shorthand for any conspiracy theory.