a prefix occurring before stems beginning with a vowel or h in loanwords from Greek, where it means “not,” “without,” “lacking” (anarchy; anecdote); used in the formation of compound words: anelectric.
Also before a consonant, a-.
Origin of an-1
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
before a consonant a-
Word Origin for an-
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
privative prefix, from Greek an-, "not, without," related to ne- and cognate with Sanskrit an-, Latin in-, Gothic and Old English un- (see un- (1)).
form of Latin ad- before -n- (see ad-).
Online Etymology Dictionary, © 2010 Douglas Harper
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.