but for

/B AH1 T F AO0 R/
adjective
  1. 1

    Pertaining to a test of causation whereby an agent or action is considered to have caused an event (and therefore to be responsible and/or liable for said event) if, had said agent or action not existed, the event would not have taken place.

preposition
  1. 1

    Except, except for, not counting; were it not for.

Source: https://en.wiktionary.org/wiki/but%20for