Marrow

n. [A-S. mearġ, mearh, O. Sax. marg, D. marg, merg, Icel. mergr, Sw. märg, Dan. marv, O. H. Ger. marg, marc, marac, M. H. Ger. marc, N. H. Ger. mark; Corn. maru, W. mer.]

1. (Anat.) A soft, oleaginous substance contained in the cavities of animal bones; medulla.
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 and his marrow, for fear of ill end. Tusser. Spinal marrow (Anat.), an elongated mass of marrow occupying the tube formed by the connected vertebræ; the spinal cord.