The term 'Fenestra' is an 8-letter word which refers to a small anatomical opening, as in a bone. It is derived from the Latin word for window, and is used to describe any small opening in the body. Fenestrae are commonly found in bones, such as the skull, and can also be found in other organs, such as the heart. They are important for allowing blood vessels, nerves, and other structures to pass through the bone or organ.