mar'-o (moach, chelebh, shiqquy, machah, "to make fat," "to grease"; muelos): Marrow is the nourisher and strengthener of the bones; it is said to moisten the bones: "The marrow (moach) of his bones is moistened" (Job 21:24). The fear of Yahweh "will be health to thy navel, and marrow (shiqquy, margin "refreshing, Hebrew moistening") to thy bones" (Pr 3:8). Thus, the expression is used figuratively of the things which alone can satisfy the soul: "My soul shall be satisfied as with marrow (chelebh, "fat") and fatness" (Ps 63:5); "In this mountain will Yahweh of hosts make unto all peoples a feast of fat things, a feast of wines on the lees, of fat things full of marrow (memuchayim, particle, plural, Pual of machah), of wines on the lees well refined" (Isa 25:6). In the Epistle to the Hebrews the writer speaks of the word of God, which is "living, and active, and sharper than any two-edged sword, and piercing even to the dividing of soul and spirit, of both joints and marrow" (Heb 4:12).
⇒See the definition of marrow in the KJV Dictionary
H. L. E. Luering