marrow

n. 1 large fleshy usu. Striped gourd eaten as a vegetable. 2 soft fatty substance in the cavities of bones. 3 essential part.  to the marrow right through. [old english]

n. The tissue which fills the cavities of most bones; the medulla. In the larger cavities it is commonly very fatty, but in the smaller cavities it is much less fatty, and red or reddish in color.