There’s probably no simpler dictionary on the web than WordSource. Simply type www.word.sc into your browser, add the word you want (such as kohlrabi) and, ba-da-boom, you have a link to your word (www.word.sc/kohlrabi). It’s that simple to find a word.
There are also thesaurus functions that are almost as simple. Just type in www.world.sc/thes/kohlrabli and you’ll get the synonyms for you word.
Tres simple.