Question: What is the meaning of the Irish term that the name of the county where Alistair Slater was killed comes from?

Context paragraphs:
Tarbert, County Kerry: Tarbert (Irish: "Tairbeart" , from an Old Irish term meaning "draw-boat", i.e. portage) is a town in the north of County Kerry, with woodland to the south and the Shannon estuary to the north.  It lies on the N69 coast road that runs along the estuary from Limerick before turning inland at Tarbert towards Listowel, and has two schools Tarbert Primary and Tarbert Comprehensive.

Fir Fálgae: Fir Fálgae is an Irish term of varying definition, but generally referring to the people of the Isle of Man.  It may have originated in the 10th century, and normally designated 'men of [the Isle of] Man'.  However, British Library iii 755.22494 glosses it "i.Inse Gall indiu" ("nowadays the Hebrides").  This seems to denote changes in ethnic designation of the Norse-Irish or the Gall Gaidel, perhaps in connection with the territorial changes of the Kingdom of Mann and the Isles.

CIÉ No. CC1: Córas Iompair Éireann No.  CC1, generally known as the Turf Burner, was a prototype 0-6-6-0 articulated steam locomotive designed by Oliver Bulleid to burn turf (an Irish term for peat used as fuel) and built at CIÉ's Inchicore Works in Dublin.  CC1 shared some, but not all, of the characteristics of Bulleid's previous attempt to develop a modern steam locomotive, the Leader.  Like the one completed Leader, CC1 had a relatively short career and was never used in front-line service.  It was the last steam locomotive to be constructed for an Irish railway.

Ó Scannail: Ó Scannail is the name of a sept in Ireland and the name derived from the Irish term "scannal", contention, or strife.

County Fermanagh: County Fermanagh ( ; from Irish: "Fir Manach "or" Fear Manach" , meaning "men of Manach" ) is one of the six counties of Northern Ireland.  The county covers an area of 1,691 km² (653 sq mi) and has a population of about 61,805.  Enniskillen is the county town and largest in both size and population.  It is also one of the thirty-two traditional counties of Ireland, as well as part of the historic province of Ulster.

Alistair Slater: Sergeant Alistair Slater, MM (25 July 1956 – 2 December 1984), was a British Army soldier who served in B Squadron, Air (7) Troop, 22 Special Air Service (SAS), who was killed on 2 December 1984 while on operations against the Provisional Irish Republican Army in Kesh, a village in County Fermanagh in Northern Ireland.

Aos Sí: The aos sí (] , older form aes sídhe ] ) is the Irish term for a supernatural race in Irish mythology and Scottish mythology (usually spelled Sìth, however pronounced the same), comparable to the fairies or elves.  They are said to live underground in fairy mounds, across the western sea, or in an invisible world that coexists with the world of humans.  This world is described in the "Lebor Gabála Érenn" as a parallel universe in which the "aos sí" walk amongst the living.  In the Irish language, "aos sí" means "people of the mounds" (the mounds are known in Irish as "the "sídhe").  In Irish literature the people of the mounds are also called daoine sídhe ] ; in Scottish mythology they are daoine sìth.  They are variously said to be the ancestors, the spirits of nature, or goddesses and gods.

Scotia's Grave: Scotia's Grave or "Scota's grave" (Irish: "Gleann Scoṫín" or "Glen of the Wee Blossom Princess Scota") is an area just south of Tralee in County Kerry beside the Finglas rivulet in Trughanacmy.  It marks what is reputed to be the grave of Scota, a daughter of an Egyptian Pharaoh known as Friel.  The traditional name of the location is Glenn Scoithin, 'vale of the little flower' or 'wee blossom.'  "Scoithín" is the diminutive of "Scoṫ," (the 't' may be aspirated as ṫ).  Scotland's name comes from the Irish language, and refers to the Irish colonists that brought Gaelic culture there.  The Irish called themselves "Scots" or "the people of the Princess Scota, per their ethnogenesis mythology.  Other names the Irish used for themselves include Milesians and Gael.  The woman's name ultimately means "blossom" ("scoṫ" or "scoth" meaning "blossom" and "Scoṫín" or "Scothín" meaning "wee blossom") as noted in the Irish epic history Foras feasa ar Eirinn - A Basis of Knowledge on Ireland.

McInerney: The name McInerney is of noble Irish origin where it is found in the modern Irish form of Mac an Airchinnigh (pronounced mock-on-arc-kenny) and in the old and literary form of Mac an Oirchinnigh and Mac an Oirchindig.  The pronunciation of Mac an Oirchinnigh has led the name to be sometimes anglicised as McEnherheny in Irish documents from the 16th–19th centuries.  The name is derived from the Irish Mac an Oirchinnigh, meaning ‘son of the erenagh’, (erenagh in Irish being 'airchinneach') literally meaning 'son of the Lord of church lands'.  The Irish word airchinneach may derive from its twin components of ‘air’ (noble) and 'ceann' (head), therefore meaning a ‘noble-head’ or ‘Lord’, denoting its aristocratic status in medieval Ireland.  The coat of arms is three red lions passant, and the motto is "Veritas" meaning "Truth".  In some places, the motto can be found as "Vincit Veritas", meaning "Truth Conquers", or "Truth Prevails".

Doon, County Cavan: Doon is the name of three townlands in County Cavan, Ireland, with one situated in the civil parishes of Drumreilly, Mullagh, and Tomregan.  All three derive their name from the Irish term "Dún", meaning "fort".

Supporting paragraphs: Alistair Slater County Fermanagh
Answer: men of Manach