a·poph·y·sis (?-p?f??-s?s)n. pl. a·poph·y·ses (-s?z?) 1. Anatomy A natural swelling, projection, or outgrowth of an organ or part, such as the process of a vertebra.2. Geology A branch from a dike or vein.[New Latin, from Greek apophusis, from apophuein, to send out branches : apo-, apo- + phuein, to grow; see bheu?- in Indo-European roots.]a·poph?y·sate? (-s?t?), a·poph?y·se?al (-s???l) adj.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.