omadhaun

noun1

1. •
   (Ireland) A fool or simpleton; someone out of their senses.

   • "Av haith!" sez Tom, burstin' out laughin'. "Shure you don't take me to be sich an omedhaun as to b'lieve that?" "Do as ye plase," sez he, "but what I tell ye is the raal thruth." — 1850