Green’s Dictionary of Slang

(Irish) holidays.

c.1940–5		in ‘Myles na gCopaleen’ Best of Myles (1968) 52: On his holliers, you know. A great man for the sea, the brother.
1988		Magill Mar. n.p.: On holliers on Sunday nights waiting under the town clock in Ballytore for a man on a bicycle bringing silver cans of film from Athy [BS].
1998		J. O’Connor Salesman 164: And I hear you’re off on the holliers.
2001		G. Coughlan Everyday Eng. and Sl. 🌐 Holliers (n): holidays!
2006		A. Gately Tearaways 141: Our class went on our holliers this summer.
2008		S.J. Martin Rock and Hard Place 78: The important thing is, I1`m going on me holliers. Thailand! Jaysis, i can't believe it.