(n.) The predictably jagged top half of a recently broken glass bottle held at the neck by the wielder.
Mickey called Paddy's sister a whore from Revere so Lenny grabbed a bottle of Jameson; made an 'Irish knife' on the bar; and held it under Mickey's nose and made him apologize. Then they all made their peace and went out to beat up some smart kids from Harvard.
by Pauly M November 1, 2006
Bobby O'Connor whipped out his Irish knife to defend himself last night while he was being robbed, and this morning, he peeled potatoes with it.
by GrayGhost9929 August 27, 2011