What does "iff" mean?
Initialism of identification friend or foe.
Iff
/ɪf ən(d)ˈoʊn.li ɪf/ conj, name, noun
conj, name, noun ·Rare ·Advanced level
Meaning at a glance
- Primary sense: Initialism of identification friend or foe.
- Grammar: iff is listed as conj, name, noun.
- Nearest alternatives: identification friend or foe.
- Usage evidence: An integer is natural iff it is greater than or equal to 0.
How to use "iff"
- Start with the primary definition, then check the part of speech before placing the word in a sentence.
- Compare nearby synonyms to make sure "iff" carries the exact meaning, tone, and strength you need.
- Use the example sentence as a context check. If your sentence uses the word differently, confirm that the grammar still fits.
Meaning check
- Does the word fit the sentence's grammar?
- Does it match the intended tone rather than only the dictionary definition?
- Would a simpler synonym be clearer for the reader?
- Is there enough surrounding context to prevent ambiguity?
Source and review context
This entry combines structured lexical data with WordToolSet review checks. Definitions, examples, synonyms, and usage notes may come from different source tables, so the page is designed to show evidence from more than one angle before you rely on "iff" in a final draft.
If a word has several senses, prefer the sense that matches your sentence's grammar and surrounding context. A correct definition can still be the wrong choice when the sentence needs a different register, emphasis, or level of specificity.
Before you rely on this definition
Read the first definition as a starting point, then check the example, synonyms, and part of speech before treating "iff" as the right word for your sentence.
If your draft is formal, technical, persuasive, or sensitive, compare "iff" with a nearby alternative so the final choice matches both meaning and reader expectation.
Compare nearby meanings
- Use synonyms when you need a softer, stronger, simpler, or more specific word.
- Use antonyms to check the boundary of the meaning and avoid accidental contrast.
- Use the example sentence to confirm the word behaves naturally in context.
- Keep the original wording when a replacement adds complexity without improving precision.
Definition decision workflow
1. Identify the role
Check whether "iff" is acting as conj, name, noun in your sentence. A definition is only useful when the grammar matches the way the word is being used.
2. Test the nearest option
Compare it with "identification friend or foe" and other nearby choices to see whether the sentence needs a softer, stronger, or more familiar word.
3. Confirm with context
Use the example sentence below as an evidence check, then read your own sentence out loud to catch tone or rhythm problems.
Review note: Definition pages are checked for source coverage, sentence evidence, synonym support, and editorial insight before they are treated as approval-ready pages. If the evidence is too thin, the page remains available to users but is kept out of the approval-facing indexed inventory.
Final meaning check
Before publishing a sentence with "iff", ask whether the word helps the reader understand the idea faster. A precise word should reduce confusion, not simply make the sentence look more polished.
When the definition, synonym evidence, and example context point in the same direction, the word is usually a safer choice. When they conflict, revise the sentence or choose a clearer alternative.
Definitions
Noun
- 1 Initialism of identification friend or foe. abbreviation, alt-of, initialism
"Another red alert last night. Lasted only five minutes, Possibly just a friendly plane with its IFF turned off."
Conjunction
- 1 Abbreviation of if and only if. abbreviation, alt-of
"A rectangle is a square iff all four of its sides have the same length."
- 2 Obsolete spelling of if. alt-of, obsolete
"For iff the patient be aſhamed to diſcloſe hiſ wounde to the phyſician which knoweth it not , phyſicke can not helpe him."
Proper Noun
- 1 Initialism of Interchange File Format, a file format standard developed for Amiga computers. abbreviation, alt-of, initialism
- 2 Initialism of International Flavors & Fragrances abbreviation, alt-of, initialism
Synonyms
All synonyms identification friend or foe
Example
"An integer is natural iff it is greater than or equal to 0."
Common questions
What is a synonym for "iff"?
Common synonyms include: identification friend or foe.
How do you use "iff" in a sentence?
An integer is natural iff it is greater than or equal to 0.
How do you pronounce "iff"?
Pronounced /ɪf ən(d)ˈoʊn.li ɪf/.