Iff

usgb/ɪf/
conjunction

Abbreviation for 'if and only if', used when both parts of the statement must be true or false together.

In mathematics, you could say 'A equals B iff B equals A'.
Visual representation of "iff" - abbreviation for 'if and only if', used when both parts of the statement must be true or false together

Often appears as...

  • iff condition
  • iff statement

Usage tips

Formal

Technical, Academic

Definition 1 of 1
Visual representation of "iff"
LampPro Tip 1/3

Mathematical Precision

Used for precise conditions in math and logic, where 'if' alone is insufficient.

Illustration for Mathematical Precision
A square is a rectangle iff all angles are 90 degrees.
LampPro Tip 2/3

Not Common Speech

Rare in everyday language; primarily found in technical or academic contexts.

Illustration for Not Common Speech
He's not using 'iff' because it's a casual conversation, not a math class.
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Double F Not Mistake

'iff' isn't a typo for 'if'; the double 'f' is intentional to mean a stronger condition.

Illustration for Double F Not Mistake
I'll agree iff you provide concrete evidence.
Visual representation of the word "Iff"

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