a combining form that represents the outcome of archi- in words borrowed through Latin from Greek in the Old English period; it subsequently became a productive form added to nouns of any origin, which thus denote individuals or institutions directing or having authority over others of their class (archbishop; archdiocese; archpriest). More recently, arch-1 has developed the senses “principal” (archenemy; archrival) or “prototypical” and thus exemplary or extreme (archconservative); nouns so formed are almost always pejorative.
Origin of arch-1
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
chief; principal; of highest rankarchangel; archbishop; archduke
eminent above all others of the same kind; extremearchenemy; archfiend; archfool
Word Origin for arch-
ultimately from Greek arkhi-, from arkhein to rule
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
also archi-, word-forming element meaning "chief, principal; extreme, ultra; early, primitive," from Latinized form of Greek arkh-, arkhi- "first, chief, primeval," comb. form of arkhos "chief" (see archon).
Online Etymology Dictionary, © 2010 Douglas Harper