KanjiJLPT N1
Marrow

marrow, pith, essence

Mnemonic

A skeleton staggers down a lonely path, desperate to possess once more what was ripped from inside its bones — its marrow. Without marrow, the skeleton is hollow and brittle, crumbling with every step along the path. It must possess that glowing core again.
Additional thoughts
Visualize a rattling, hollow skeleton chasing a glowing orb of marrow floating down a winding path. It reaches out to possess it — marrow is the skeleton's deepest essence, what makes bones alive.
Quick recall
A skeleton on a path yearns to possess its lost marrow.

Details

The keyword for 髄 is marrow. This kanji refers to the soft, vital substance found inside bones, known as bone marrow, as well as the spinal marrow or spinal cord. By extension, it conveys the idea of the innermost essence or core of something, the very heart of a matter. It is used both in medical and anatomical contexts and figuratively to describe reaching the deepest, most fundamental part of an idea or experience.
On'yomi
ずい