| ironisk | ironic |
| ironiskt | ironically |
| irra | go astray |
| irrande | devious |
| irrationell | irrational |
| irrationellt tal | surd |
| Irrawaddy | Ayeyarwady River |
| Irrawadidelfin | Irrawaddy Dolphin |
| irrbloss | will-o'-the-wisp |
| Irredentism | Irredentism |
| Irreducibel komplexitet | Irreducible complexity |
| irrelevans | irrelevance |
| irrelevant | extraneous |
| irreligiös | irreligious |
| irreparabel | irreparable |
| irreversibelt fenomen | irreversibility of the phenomenon |
| irrgång | maze |
| irritabel | irritable |
| irritation | annoyance |
| irritera | rile |
