(from Irish bainsídhe/beansídhe, "female fairy") (M-W), "woman of the fairies" (AHD) or "...of a fairy mound" (RH). The Modern Irish word for woman is bean /bæn/ and síd(h) (or sí in modern spelling) is an Irish term referring to a 'fairy mound'. (See Sidhe.) However, in traditional Irish mythology a banshee is seen as an omen of death.
O.Ir. clocc meaning "bell"; into Old High German as glocka, klocka (whence Modern German Glocke) and back into English via Flemish; cf also Welsh cloch but the giving language is Old Irish via the hand-bells used by early Irish missionaries.
fun, used in Ireland for fun/enjoyment. The word is actually English in origin; it entered into Irish from the English "crack" via Ulster Scots. The Gaelicised spelling craic was then reborrowed into English. The craic spelling, although preferred by many Irish people, has garnered some criticism as a faux-Irish word.
The ultimate source of this word is Latin crux, the Roman gibbet which became a symbol of Christianity. Some sources say the English wordform comes from Old Irish cros. Other sources say the English comes from Old French crois and others say it comes from Old Norse kross.
(from drom/druim meaning "ridge") a ridge often separating two long narrow valleys; a long narrow ridge of drift or diluvial formation. Drumlin is a linguistic diminutive of drum, and it means a small rounded hill of glacial formation, often seen in series (OED). A landscape of many Drumlins occurs in some parts of Ireland (including counties Cavan and Armagh). Drumlin is an established technical word in geology, but drum is almost never used.
to finish, to put an end to: "That's put the kibosh on it". The OED says the origin is obscure and possibly Yiddish. Other sources, suggest that it may be from the Irish an chaip bháis meaning "the cap of death" (a reference to the "black cap" worn by a judge passing sentence of capital punishment, or perhaps to the gruesome method of execution called pitchcapping); or else somehow connected with "bosh", from Turkish "boş" (empty). (Caip bháis - pronounced as kibosh - is also a word in Irish for a candle-snuffer.)
(from loch) a lake, or arm of the sea. According to the OED, the spelling "lough" was originally a separate word with a similar meaning but different pronunciation, perhaps from Old Northumbrian: this word became obsolete, effectively from the 16th century, but in Anglo-Irish its spelling was retained for the word newly borrowed from Irish.
(from sluagh-ghairm meaning "a battle-cry used by Gaelic clans") Meaning of a word or phrase used by a specific group is metaphorical and first attested from 1704.
small fragments, atoms. In phrases such as 'to explode into smithereens'. This is the word smithers (of obscure origin) with the Irish diminutive ending. Whether it derives from the modern Irish smidrín or is the source of this word is unclear (OED).
(from tuilleadh meaning "a supplement") used to refer to an additional article or amount unpaid for by the purchaser, as a gift from the vendor (OED). Perhaps more prevalent in Newfoundland than Ireland. James Joyce, in his Pomes Penyeach included a thirteenth poem as a bonus (as the book sold for a shilling, twelve poems would have come to a penny each), which he named "Tilly," for the extra sup of milk given to customers by milkmen in Dublin.