ORGAN n. 6 definitions
apable of performing some special action (termed its function), which is essential to the life or well-being of the whole; as, the heart, lungs, etc., are organs of animals; the root, stem, foliage, etc., are organs of plants.
PALEOZOIC a.
Of or pertaining to, or designating, the older division of geological time during which life is known to have existed, including the Silurian, Devonian, and Carboniferous ages, and also to the life or rocks of those ages. See Chart of Geology.