In 1874, Richard Cleasby and Gudbrand Vigfusson published their monumental Icelandic-English Dictionary, which still remains a prime source for Anglo-Norse researchers.
The dictionary has more than 26,000 entries, all of which can be searched here.
This search engine utilises the dataset produced by Sean Crist for the Germanic Lexicon project, and which he has kindly allowed the Hjaltland Network to use.