Cask attachment is a term that refers to a device used for drawing the beer from casks. There are various synonyms for the word 'cask attachment' such as cask breather, cellar breather, beer engine, hand pump, and gravity tap. A cask breather is a device that is used to regulate the pressure inside the cask, while a cellar breather is used to ensure that the beer in the cellar is kept fresh. A beer engine is a device that draws beer from the cask using a hand pump that helps to regulate the flow of beer. A gravity tap is another term for a cask attachment that uses gravity to dispense beer, without the use of any external devices.