This is possible because language is not the only symbolic means of communication. In order to prove that chimpanzees and gorillas are capable of language, and not simply a different kind of symbolic communication system, they must learn a sign language with the basic characteristics of human language.
Definition of Halloween. : October 31 observed especially with dressing up in disguise, trick-or-treating, and displaying jack-o'-lanterns during the evening.
Evolving from the ancient Celtic holiday of Samhain, modern Halloween has become less about literal ghosts and ghouls and more about costumes and candy. The Celts used the day to mark the end of the harvest season and the beginning of winter, and also believed that this transition between the seasons was a bridge to the world of the dead.