An Icelandic-English dictionary, based on the ms. collections of the late Richard Cleasby. Enl. and completed by Gudbrand Vigfússon. With an introduction and life of Richard Cleasby by George Webbe Dasent.
Download the dictionary from here:
https://archive.org/details/icelandicenglish00cleauoft
An online searchable version of the dictionary is available here:
http://www.ling.upenn.edu/~kurisuto/germanic/oi_cleasbyvigfusson_about.html