not if, but when

adverb

Inevitably.

“Not if, but when your files eventually get corrupted, you'll turn into the kind that makes back-ups.”

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Meanings

adverbnot if, but when (not comparable)
  1. not comparableInevitably.

    Not if, but when your files eventually get corrupted, you'll turn into the kind that makes back-ups.

Origin

Used as an intensifier when a scenario is considered extremely likely, such that if (implying low likelihood) is not sufficient to represent its probability of occurrence. (Whereas if implies only possibility, when implies certainty, where only the time that something happens is unknown.)

Full word history & related roots →
Cite this entry
APA

not if, but when. (n.d.). In WatkinsX Dictionary. Retrieved November 5, 2026, from https://dictionary.watkinsx.com/word/not%20if%2C%20but%20when

MLA

“not if, but when.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/not%20if%2C%20but%20when. Accessed November 5, 2026.

Chicago

WatkinsX Dictionary, s.v. “not if, but when,” accessed November 5, 2026, https://dictionary.watkinsx.com/word/not%20if%2C%20but%20when.

Source: not if, but when on Wiktionary, CC BY-SA 4.0.