| English | Part of Speech | Gaelic |
|---|---|---|
| ice-shelf | n(f) | sgeilp-deighe |
| igneous rock | n(f) | clach theinnteach |
| in series (electric) | adj | sreathach |
| incisor | n(f) | clàr-fhiacail |
| inner core (of the earth) | n(m) | cridhe eitean na talmhainn |
| interval | n(m/f) | beàrn |
| ionosphere | n(m) | aidhonospeur |
| isosceles | adj | co-chasach |
| isoscles | adj | co-chasach |
| isoscles triangle | triantan co-chasach |