pith
noun
°The soft spongy substance in the center of the stems of many plants and trees.
°The essential or vital part of an idea or theory or something else.
verb
°To extract the pith from (a plant stem or tree).
°To kill (especially cattle or laboratory animals) by cutting or piercing the spinal cord.
synonyms: core, essence, tenor, gist more» , heart, heart and soul, inwardness, kernel, marrow, meat, nitty-gritty, nub, quintessence, soul, spirit, stuff, substance