| Main Entry: | zero day1 |
| Part of Speech: | n |
| Definition: | the day on which a computer security vulnerability is exploited before security experts can address it |
| Etymology: | 2000 |
| Main Entry: | zero day2 |
| Part of Speech: | n |
| Definition: | a day when software, videos, music, or information is obtained prior to the day of public release; also called 0day |