Dictionary.com
definitions

az-

  1. variant of azo-, especially before a vowel: azine.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
az- in Science

azo-

az-
  1. A prefix that means “containing an azo group attached at both ends to other groups,” as in the compound azobenzene.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.