| Acronym | Meaning |
| IIIO | Intel Inside, Idiot Outside |
| IIMAD | If It Makes A / Any Difference |
| IIR | If I Recall |
| IIR | If I Remember |
| IIRC | If I Recall Correctly |
| IIRC | If I Remember Correctly |
| IIT | Is It Tight? |
| IITLYTO | If It's Too Loud You're Too Old |
| IITYWIMWYBMAD | If I Tell You What It Means Will You Buy Me A Drink? |
| IITYWYBMAD | If I Tell You Will You Buy Me A Drink? |
| IIWM | If It Were Me |
| IJPMP | I Just Pissed My Pants |
| IJWTK | I Just Want To Know |
| IJWTS | I Just Want To Say |
| IKALOPLT | I Know A Lot Of People Like That |
| IKWYM | I Know What You Mean |
| IKYABWAI | I Know You Are But What Am I? |
| ILA | I Love Acronyms |
| ILICISCOMK | I Laughed, I Cried, I Spat/Spilt Coffee/Crumbs/Coke On My Keyboard |
| ILU | I Love You |
| ILUAAF | I Love You As A Friend |
| ILY | I Love You |
| IM | Instant Messaging |
| IM2BZ2P | I AM Too Busy To Pee |
| IMA | I Might Add |
| IMAO | In My Arrogant Opinion |
| IMBLUV | It Must Be Love |
| IMCO | In My Considered Opinion |
| IME | In My Experience |
| IMEZRU | I Am Easy, Are You? |
| IMHEIUO | In My High Exalted Informed Unassailable Opinion |
| IMHO | In My Humble Opinion |
| IMI | I Mean It |
| IMNERHO | In My Not Even Remotely Humble Opinion |
| IMNSHO | In My Not So Humble Opinion |
| IMO | In My Opinion |
| IMOO | In My Own Opinion |
| IMPOV | In My Point Of View |
| IMRU | I Am, Are You? |
| IMS | I Am Sorry |
| INBD | It's No Big Deal |
| INMP | It's Not My Problem |
| INNW | If Not Now, When? |
| INPO | In No Particular Order |
| INUCOSM | It's No Use Crying Over Spilt Milk |
| IOH | I'm Outta Here |
| ION | Index Of Names |
| IOUD | Inside, Outside, Upside Down |
| IOW | In Other Words |
| IPN | I'm Posting Naked |