wiktionaryis a wiki based open content dictionary

an online medical dictionary

Australian slang website lists localised language for those in Australia

for astrobiological terms

net lingo online dictionary

can't think of the right cybernetic term? check the cybernetics web dictionary..

dictionary.com - a good resource to quickly check spelling. http://www.dictionary.com

reverse lookup dictionary - search for a concept and this site provides a list of terms. it's great for those 'the word is on the tip of my tongue' moments. visit http://www.onelook.com/reverse-dictionary.shtml to try it