| Acronym | Definition |
|---|
| IF | Intermediate Frequency (radio/communications systems) |
| IF | In Fact |
| IF | International Falls (city on the Minnesota/Canada border) |
| IF | India Forum (India) |
| IF | Interactive Fire (insurance) |
| IF | Interactive Fiction |
| IF | Involved Field (radiotherapy) |
| IF | Industrial Facilities |
| IF | Institute for the Future |
| IF | Industrial Fund |
| IF | Interface |
| IF | Input File (Linux command line) |
| IF | Information Flow |
| IF | Integrated Farm |
| IF | Impact Factor |
| IF | Integration Facility |
| IF | Intelligence Flight |
| IF | Intelligent Finance (Halifax Group) |
| IF | International Federation (sports) |
| IF | Interaction Forum |
| IF | Intelligence Fusion |
| IF | Integration Framework |
| IF | Immediate Frequency |
| IF | Intermediate Fix |
| IF | Ice Fog |
| IF | International Fleet (game and book) |
| IF | Internal Focusing |
| IF | Internal Flush |
| IF | Interference (Dutch electro artist) |
| IF | Indirect Fire |
| IF | In Flames (band) |
| IF | Isolation Filter |
| IF | Isolation Function |
| IF | Initiation Factor |
| IF | Interference Filter |
| IF | Instruction Fetch |
| IF | Internally Flawless (2nd highest quality of diamond) |
| IF | Infertility |
| IF | Internal Fixation |
| IF | Intermittent Fasting (dieting) |
| IF | Intrinsic Factor |
| IF | Incremental Funding |
| IF | Information Directorate (at AFRL) |
| IF | Instantaneous Frequency |
| IF | Intermediate Filament (genetics) |
| IF | Idaho Falls (Idaho) |
| IF | Intrinsically Funny |
| IF | Interstitial Fluid |
| IF | Infield (baseball/softball) |
| IF | Interferon |
| IF | Infielder |
| IF | Ironforge (World of Warcraft city) |
| IF | Immunofluorescence |
| IF | InvisionFree (Invision Power Board) |
| IF | Intermediate Filament (cytoskeletal component) |
| IF | Induction Furnace (metal melting) |
| IF | Ifosfamide |
| IF | Independent Force |
| IF | International Fleet (Ender's Game novel) |
| IF | Interrupt Flag |
| IF | Indemnité Forfaitaire (French: Liquidated Damage) |
| IF | Instant Form (software) |
| IF | Interferential Stimulation |
| IF | Interference Field |
| IF | Intruders Foundation |
| IF | Intake Fraction (the fraction of a pollutant which is inhaled by humans) |
| IF | Interface Freeze |
| IF | Intrinsic Free (steel) |
| IF | Intermediate Forward |
| IF | Infra-Free |
| IF | Inland Fetch (line) |
| IF | Ingenico Fortronic Ltd |
| IF | Intelligent Field Co., Ltd. (Japan) |
| IF | Intercept and Broadcast (US Navy) |
| IF | Internationally Flawless (diamonds) |