Green’s Dictionary of Slang

(Irish) very drunk; thus fluther, to render drunk.

c.1940–5		‘Myles na gCopaleen’ Best of Myles (1968) 101: Remember well, many’s a county council meeting, fluther-eyed note-takers couldn’t get the half of it, stuff that days was spent thinkin’ out. [Ibid.] 338: Drunk; jarred; fluthered [...] fluthery-eyed; spiflicated; screwed; tight.
1942		S. O’Faolain Bell IV 38: I’d like to be drunk — fluthered up to the eyes! Then I’d tell them all in the house what I think of them.
1949		J.D. Sheridan Magnificent MacDarney 133: ‘Don’t mind me, Dan,’ he went on after a little while. ‘I’m fluthered. That’s what’s the matter. Fluthered’.
1969		P. Boyle All Looks Yellow to the Jaundiced Eye 32: By this time we were all getting a bit mouldy, but poor bloody Joe was properly fluthered.
1974		Star Press (Muncie, IN) 24 Oct. 23/2: The Irish have at least two dozen words for inebriation [...] killarneyed, fluthered, stotious, pallatic, maggoty, blithero, half-tore, paralytic and stoven.
1996		Sun. Indep. (Dublin) 21 April n.p.: The men exchange reminiscences about the time they got fluthered at one sports event or another [BS].
2001		G. Coughlan Everyday Eng. and Sl. 🌐 Fluthered (a): drunk.
2007		A.M. Greeley Irish Linen 93: I treated myself to a second jar of Middleton’s, aware that if I came home fluthered, I’d be banished [...] Well, that had never happened, because it takes at least three jars to fluther me.