blather/blether

[n. & vb., from Middle English blather (n.), nonsense (Scottish form blether more common in Ulster), from Old Norse blathra (vb.), talk nonsense; Irish bladar , flatter(y), coax(ing)].

[Talk] loquacious nonsense; one who indulges in such.

1925 Louise McKay, Mourne Folk : ... Och, Dandy, ye're a blether; but I forgive ye, for ye're too ould to take any notice of"'

1955 James Plunkett, The Trusting and the Maimed , 'Mercy': "'What are you blathering about?" Toner asked in terror.'

Also blatherskite/blatherumskite [n.]. S.o. who talks thus, or the talk itself. 1904 George Bemard Shaw John Bull's Other Island : 'DORAN There's too much blatherumskite in Irish politics, a dale too much.'

1938 Seumas MacManus, The Rocky Road to Dublin: 'a gathered group of neighbours, discussing the fight in Daincy Gillespie the cooper's, were drowned out by a deluge of blatherskite from Dainey's gabbier wife'.

1986 Padraic O'Farrell, 'Tell me, Sean O'Farrell': 'He [the priest] knocked a poor strammel (thin man) into a big bin of flour in jones's public house in Clane one night. Belted him right into it for giving some ould bletherumskite.'

Hence blathery

From Slanguage - A Dictionary of Irish Slang, Bernard Share, Gill and MacMillian 1997. (0-7171-2683-8)

Ok - this is all well and fine - but why call it *Blather*?

And also...

Mhi/nigh Toma/s de Bhaldraithe bunu/s an fhocail in "Celtica" XX (1988):

Tá an focal "bleachtaire" seanbhunaithe i nGaeilge na haoise seo sa chiall 'detective'. Ciall nua é sin a tugadh don fhocal. In "Irisleabhar na Gaedhilge" IX (1899) 356 atá an sampla is túisce atá aimsithe agam. Cé nach bhfuil sé in DIL, tá "bliochtaire" le fáil in Pl[uincéad] sv. 'lactarius' (fear bainne, bliteoir). Is cosúil gur measadh gurb é príomhghnó an 'detective' eolas a mhealladh ó dhuine le 'sámhbhriathra cluanacha", is é sin an t-eolas a 'bhleán' uaidh le plásaíocht. Tá an bhrí mheafartha in Pl. freisin, e.g. "blighim" sv. 'adulo', "blidheadh" sv. 'palpatio'. Tá an bhrí sin fós leis sa Ghaeltacht, e.g. "Bhí sé ag gabhail daoithe á blanndar agus á bliodhgan ach ní raibh maith dó a bheith léithe." Cf. "blite" = 'plámásach' agus "bliteog" = 'súdaire' i gCois Fharraige.

"bleachtaire", mar seo: 'bleachtaire or bliochtaire, a wheedler, a soothing, undermining fellow who strives to steal into your confidence in order to come at some secrets, and then to betray them. Metaph. from soothing a cow's milk'.

Seo mar atá ag OR.: 'bleachtaire, a person who milks cows; a wheedler, a soother; a person who by soft speeches endeavours to steal into your confidence, to turn it to his own advantage. "Anglice" blather.' [...]