From WordNet (r) 3.0 (2006) [wn]:
murphy
n 1: an edible tuber native to South America; a staple food of
Ireland [syn: potato, white potato, Irish potato,
murphy, spud, tater]
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Murphy \Mur"phy\, n.
A potato. [Humorous] --Thackeray.
[1913 Webster]