A Dictionary of the Targumim, the Talmud Babli and Yerushalmi, 
and the Midrashic Literature. 
by Marcus Jastrow
London: Luzac & Co.
New York: G.P. Putnam's Sons, 1903
VOLUME I: ALEPH to KAPH (60MB file, slow download)
VOLUME II: LAMED to TAW (188 MB file, slow download)
 
VOLUMES I & II (using a Hebrew Menu)