apophysis

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Anatomy A natural swelling, projection, or outgrowth of an organ or part, such as the process of a vertebra.
• noun Geology A branch from a dike or vein.

from The Century Dictionary.

• noun In anatomy: Any process of bone; an out-growth of bone; a mere projection or protuberance, which has no independent ossific center, and is thus distinguished from an epiphysis (which see); specifically, any process of a vertebra, whether it has such a center, and thus is epiphysial in nature, or not: in the former case, a vertebral apophysis is called autogenous or endogenous; in the latter, exogenous. A process or outgrowth of some organ of the body, as the brain: as, apophysis cerebri, the pituitary body. See cut under brain. In chitons, a process of one of the plates, inserted into the mantle.
• noun In botany, a swelling under the base of the theca or spore-case of some mosses, as in species of Splachnum. See cut under Andreæa.
• noun In geology, a term applied to the arms which often extend outward in a horizontal direction from the main mass or dike of an intrusive igneous rock.
• noun In architecture, same as apophyge.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Anat.) A marked prominence or process on any part of a bone.
• noun (Bot.) An enlargement at the top of a pedicel or stem, as seen in certain mosses.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun anatomy A natural outgrowth, swelling or enlargement, usually of an organism; A protuberance on a bone.
• noun geology A branch of a dike or vein

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun (botany) a natural swelling or enlargement: at the base of the stalk or seta in certain mosses or on the cone scale of certain conifers
• noun (anatomy) a natural outgrowth or projection on an organ or body part such as the process of a vertebra