# unless

Pronunciation: US say "un-LES" /ənˈlɛs/; UK

## Conjunction

1. Except if; if not: introduces the one condition under which the main statement would not happen or not be true.
   - Simple: Except if. It tells you the one thing that would stop something from happening or being true.
   - _The flight will depart on time unless the weather worsens._
   - _Employees may not share client data unless the client has given written consent._

## Origin

Middle English unlesse began as on lesse (today's "on" + "less"), taken from "(not) on lesse (than)," that is, "(not) on a less compelling condition (than)." Because the word went unstressed and carried a negative sense, its "on" turned into "un-."

Source: DictionaryAI, https://dictionaryai.com/define/unless (written from Wiktionary data, CC BY-SA 4.0: https://creativecommons.org/licenses/by-sa/4.0/).