What is the meaning of Marrow?

The substance inside bones which produces blood cells.

A kind of vegetable like a large courgette/zucchini or squash.

The pith of certain plants.

The essence; the best part.

Inner meaning or purpose.

Bone marrow biopsy.

Semen.

A friend, pal, buddy, mate.

A miner's mate or assistant.

One of a pair; a match; a companion; an intimate associate.

Source: wiktionary.org