What is a poltergeist? According to dictionary.com the definition of a poltergeist is:
a ghost or spirit supposed to manifest its presence by noises, knocking, etc.
The origin of the word can be traced back to the German word of polter to make noise, knock, rattle + geist which means ghost. The word has been around since the 1840’s.
The British Dictionary definition makes mention of the noises but also the acts of mischief a poltergeist can do such as throwing furniture around. “In the native idiom of Northern England, such phenomenon likely would be credited to a boggart.” (2017, Dictionary.com)