| Irredentism | Iredentizem |
| Irregular moon | Nepravilni satelit |
| Irregular satellite | Nepravilni satelit |
| irreversibility of the phenomenon | nepovratnost |
| irrigation | umetno namakanje |
| irrigation farming | namakalno kmetijstvo |
| irrigation system | namakalni sistem |
| Irréversible | Nepovratno |
| Irtysh | Irtiš |
| Irtysh River | Irtiš |
| Irving Berlin | Irving Berlin |
| Irving Langmuir | Irving Langmuir |
| IS | IS |
| Isaac Abrabanel | Isaac Abrabanel |
| Isaac Albéniz | Isaac Albéniz |
| Isaac Asimov | Isaac Asimov |
| Isaac Barrow | Isaac Barrow |
| Isaac Newton | Isaac Newton |
| Isabel Allende | Isabel Allende |
| Isabel Allende Bussi | Isabel Allende |
| Isadora Duncan | Isadora Duncan |
| Isar | Isar |
| Iseo | Tristan in Izolda |
| Isfahan | Isfahan |
| Isfahan Province | Isfahan |
| Ishim | Išim |
| Ishim River | Išim |
| Ishtar | Inana |
| Isidor Isaac Rabi | Isidor Isaac Rabi |
| Isidore of Seville | Sveti Izidor Seviljski |
| Isis | Izida |
| Isla Aves | Ptiči |
| Isla de Aves | Ptiči |
| Isla Grande de Tierra del Fuego | Ognjena zemlja |
| Isla Margarita | Margarita |
| Islam | islam |
| Islamic | Islam |
| Islamic calendar | Islamski koledar |
| Islamic calligraphy | Pisava |
| Islamic Republic of Iran | Iran |
| Islamic Republic of Mauritania | Mavretanija |
| Islamic Republic of Pakistan | Pakistan |
| Islamic view of Aaron | Aron |
| Islamic view of Abraham | Abraham |
| Islamic view of Adam | Adam in Eva |
| Islamic view of Lot | Lot |
| Islamic view of Moses | Mojzes |
| Islamism | Islam |
| Islamitic | Islam |
| Islamophobia | islamofobija |
| island | otok |
| island ecosystem | otoški ekosistem |
| Island of California | Kalifornija |
| Island of Mozambique | Mozambik |
| isle | otok |
| Isle of Man | Man |
| Isle of Mann | Man |
| Isle River | Isle |
| Islote Horacio | Horacij |
| Ismaël Bullialdus | Ismael Bullialdus |
| İsmet İnönü | Mustafa Ismet Inöni |
| ISO | Mednarodna organizacija za standardizacijo |
| Iso Rivolta | Mednarodna organizacija za standardizacijo |
| ISO standard | ISO standard |
| Isobaric process | Izobarna sprememba |
| Isochoric process | Izohorna sprememba |
| Isolated singularity | Odpravljiva singularnost |
| Isolated sytem | Toplotno izoliran sistem |
| isomer | izomer |
| Isonoe | Isonoja |
