1. a prefix occurring in loanwords from Greek, where it meant “upon,” “on,” “over,” “near,” “at,” “before,” “after” (epicedium; epidermis; epigene; epitome); on this model, used in the formation of new compound words (epicardium; epinephrine).
Also ep-, eph-.

Origin of epi-

< Greek, prefixal use of epí, preposition and adv.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for epi-


eph- or before a vowel ep-

  1. on; upon; above; overepidermis; epicentre
  2. in addition toepiphenomenon
  3. afterepigenesis; epilogue
  4. near; close toepicalyx

Word Origin for epi-

from Greek, from epi (prep)
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for epi-

word-forming element meaning "on, upon, above," also "in addition to; toward, among," from Greek epi "upon, at, close upon (in space or time), on the occasion of, in addition," from PIE *epi, *opi "near, at, against" (cf. Sanskrit api "also, besides;" Avestan aipi "also, to, toward;" Armenian ev "also, and;" Latin ob "toward, against, in the way of;" Oscan op, Greek opi- "behind;" Hittite appizzis "younger;" Lithuanian ap- "about, near;" Old Church Slavonic ob "on"). Before unaspirated vowels, reduced to ep-; before aspirated vowels, eph-. A productive prefix in Greek; also used in modern scientific compounds (e.g. epicenter).

Online Etymology Dictionary, © 2010 Douglas Harper

epi- in Medicine


  1. On; upon:epineural.
  2. Over; above:epibasal.
  3. Around:epicystitis.
  4. Close to; near:epimer.
  5. Besides:epiphenomenon.
  6. After:epigenesis.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.