The soft, spongy tissue in the center of plant stems

• The whitish inner layer of a citrus rind

The soft inner tissue of an animal organ or body

• Especially the spinal cord; spinal marrow
• Also the spongy interior of a horn or a feather shaft

The central or innermost part of something; the core

• The soft inner portion of bread or similar foods

The essential or most vital part; the essence

• Force, vigor, or substance; concise power in speech or writing
• Grave importance or weight

To kill or render insensible by destroying the spinal cord

• To remove the pith from something; to strip of essence