how I remember it, crackers used the term before the warez groups did. it meant having a crack for software on the same day it was released. in warez it was a

how I remember it, crackers used the term before the warez groups did. it meant having a crack for software on the same day it was released. in warez it was a folder on the ftp server that would list all the latest releases from that day, to save you from navigating all the /pub/whatever folders over your slow 14.4k connection and so that the distributors would only have to grab from one place. and somehow in this history the pronunciation changed from "oh day" to "zero day" and was re-appropriated as an infosec term. edit: just read the definition in OP, it is hilarious.