What does pith mean in cooking?

pith means: Covering the citrus fruit’s flesh is the white cell lining. (in Cooking Dictionary)

What else does pith mean?

It is the soft and spongy tissue at the base of all vascular plant stems, which consists mainly of parenchyma. (in Merlin Dictionary)

A feather’s soft interior substance. (in Merlin Dictionary)

It is the essential, central or most important part. (in Merlin Dictionary)

Remove the pith (from a plant stem). (in Merlin Dictionary)

A needle is used to puncture the vertebral canal in order to sever or kill the spinal cord. (in Merlin Dictionary)

To cut the spine cord to kill cattle (in Merlin Dictionary)