assimilated form in Latin of the prefix in- prefix² before initial r, used in the same way in English, as in ir-radiate, ir-ruption. In these derivatives only one r is pronounced.

assimilated form in Latin of the prefix in- prefix³ before initial r, used in the same way in English (and much more frequent than ir- prefix¹); as in ir-rational, ir-reclaimable, ir-recoverable, ir-refragable, ir-religion, ir-revocable. In these only one r is pronounced, the prefix being really reduced to i-.