The Collaborative International Dictionary of English v.0.48:
Zed \Zed\, n. [F., probably through It. zeta, fr. L. zeta. See Zeta.] The letter Z; -- called also zee, and formerly izzard. "Zed, thou unnecessary letter!" --Shak. [1913 Webster]WordNet (r) 3.0 (2006):
zee n 1: the 26th letter of the Roman alphabet; "the British call Z zed and the Scots call it ezed but Americans call it zee"; "he doesn't know A from izzard" [syn: Z, z, zee, zed, ezed, izzard]