| Abbreviation | Definition |
|---|---|
| IRMC | Idaho Regional Mathematics Center |
| IRO | In Retrogade Order |
| IRS | Inverse Repeated Sequence |
| ISD | Increasing, Steady, or Decreasing |
| ISDA | Irregularly-Spaced Data Analysis |
| ISEA | Icosahedral Snyder Equal Area |
| ISM | Institute of Statistical Mathematics |
| ISN | Initial Sequence Number |
| ISOP | Irredundant Sum Of Products |
| ISTEM | Interdisciplinary Science Technology Engineering and Mathematics |
| ITAE | Integral of Absolute Error Multiplied by Time |
| ITC | Information Theoretic Criterion |
| ITEAM | Intermediate TEAchers of Mathematics |
| ITMC | International Talent of Mathematics Contest |
| IU | Independence of Underlined |
| IV | Image Value |
| IV | Independent Variable |
| IV | Roman Number 4 |
| IVDM | Interpolated Value Difference Metric |
| IVM | Isotropic Vector Matrix |