| Abbreviation | Definition |
|---|---|
| ISIS | I Spit In a Sack |
| ISIS | Idiotic Scumbags In Syria |
| ISM | It's So Meaningless |
| ISO | I'm So Out |
| ISO | I'm Still Online |
| ISO | In Search Of |
| ISO | Insane Sexual Offer |
| ISO | Insurance Services Organization |
| ISO | Its So Obvious |
| ISOTBOMDA | I Swear On The Bones Of My Dead Ancestors |
| ISP | I'm So Prissy |
| ISS | I Said So |
| ISSYGTI | I'm So Sure You Get The Idea |
| ISTM | It Seems To Me |
| ISWYDT | I See What You Did There |
| ISWYM | I See What You Mean |
| IT | I Think |
| IT | Is There .... |
| ITA | I Totally Agree |
| ITA/D | I Totally Agree/Disagree |