(n): a specialized part of a cell; analogous to an organ
(n): the positively charged dense center of an atom
(n): a point equidistant from the ends of a line or the extremities of a figure
(n): a small group of indispensable persons or things
(n): a group of things of the same kind that belong together and are so used
(n): (astronomy) the center of the head of a comet; consists of small solid particles of ice and frozen gas that vaporizes on approaching the sun to form the coma and tail
(n): a point equidistant from the ends of a line or the extremities of a figure
(n): any histologically identifiable mass of neural cell bodies in the brain or spinal cord
(n): a structure that is part of the nervous system
(n): the central structure of the lens that is surrounded by the cortex
(n): a particular complex anatomical part of a living thing
Wow:
"Palaeontol. The phragmocone of a belemnite. Obs." (OED)