Green’s Dictionary of Slang

(Irish) a gullible simpleton.

c.1940–5		in ‘Myles na gCopaleen’ Best of Myles (1968) 81: The ignorant self-opinionated sod-minded suet-brained ham-faced mealy-mouthed streptococcus-ridden gang of natural gobdaws!
1986		P. O’Farrell Tell me, Sean O’Farrell 15: J.J. was no daw.
1989		H. Leonard Out After Dark 28: What kind of gobdaws are yous [...] to be made eejits of be the English?
1991		T. Delaney Where We Sported and Played 67: I liked that. It meant she was no daw.
1996		Sun. Trib. (Dublin) 30 June n.p.: If you, major gobdaw who wrote in, knew anything at all about Myles [na gCoplaleen] you would know that He was not exactly behind the door when it came to such borrowings Himself [BS].