Mar·row n.
1. Anat. 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.
2. The essence; the best part.
It takes from our achievements . . .
The pith and marrow of our attribute. --Shak.
3. One of a pair; a match; a companion; an intimate associate. [Scot.]
Chopping and changing I can not commend,
With thief or his marrow, for fear of ill end. --Tusser.
Marrow squash Bot., a name given to several varieties of squash, esp. to the Boston marrow, an ovoid fruit, pointed at both ends, and with reddish yellow flesh, and to the vegetable marrow, a variety of an ovoid form, and having a soft texture and fine grain resembling marrow.
Spinal marrow. Anat. See Spinal cord, under Spinal.