| Subject | English | Irish |
| life.sc. | acid-fast stain | ruaim aigéadobach |
| immigr. | Automated Fast Track Crossing at External Schengen Borders | Mear-thrasbhealach Uathoibrithe ag Teorainneacha Seachtracha Schengen |
| transp., nautic., fish.farm. | breast fast | téad bhrollaigh |
| comp., MS | Exchange Fast Access | Mear-Rochtain Exchange (A feature that enables Exchange users to see new email messages and up-to-date calendar items as soon as they open Outlook, without waiting for it to finish synchronizing) |
| chem. | fast boiling water bath | dabhach uisce mearbhruite |
| nucl.pow. | fast breeder | imoibreoir |
| nucl.pow. | fast breeder | mear-imoibreoir pórúcháin |
| nucl.pow. | fast breeder reactor | imoibreoir |
| nucl.pow. | fast breeder reactor | mear-imoibreoir pórúcháin |
| nucl.pow. | fast breeding reactor | imoibreoir |
| nucl.pow. | fast breeding reactor | mear-imoibreoir pórúcháin |
| comp., MS | fast forward | mearchas (To advance audio or video playback at a speed that is faster than normal) |
| transp. | fast freight train | mearthraein lastais |
| health., med. | fast-growing non-Hodgkin's lymphoma | liomfóma neamh-Hodgkin ionsaitheach |
| phys.sc., nucl.phys. | fast neutron | mearneodrón |
| nucl.phys., nucl.pow. | fast neutron reactor | mear-imoibreoir |
| nucl.phys., nucl.pow. | fast reactor | mear-imoibreoir |
| environ. | fast reactor Nuclear reactor which produces more fissile material than it consumes, using fast-moving neutrons and making plutonium-239 from uranium-238, thereby increasing the reactor's efficiency | imoibreoir tapa |
| agric. | Fast Red E | dearg seasmhach E |
| market., commun. | fast rotating feed window | fuinneog fotha mhear-rothlach |
| comp., MS | fast shutdown | múchadh mear (A mechanism for a MAPI client to initiate a quick shutdown of the client process, notifying all providers with which the client has an active MAPI session to save data and settings before the client process exits) |
| environ. | fast-start financing | mearmhaoiniú tosaigh |
| environ. | fast-start financing | mearmhaoiniú |
| environ. | fast-start funding | mearmhaoiniú tosaigh |
| environ. | fast-start funding | mearmhaoiniú |
| comp., MS | fast startup | tosú tapa (A method of starting the computer that speeds boot time by ending the user session and hibernating the computer, rather than shutting down all running services) |
| market. | fast-track | mear |
| commer., polit., fin. | fast track action | mearghníomh |
| environ. | fast traffic No definition needed | trácht thapa |
| gen. | fast yellow | buí seasmhach |
| med. | fasting blood glucose | glúcós fola céalacain |
| med. | fasting blood sugar | glúcós fola céalacain |
| med. | fasting glucose | glúcós fola céalacain |
| med. | fasting triglycerides | tríghlicrídí céalacain |
| nucl.phys. | reactor with a high fast-neutron flux | imoibreoir ardfhlosca neodróin mear |
| nucl.phys. | reactor with a high fast-neutron flux | imoibreoir ardfhlosca mearneodróin |
