Using Lexipedia you can visually map out words and concepts in a clean and friendly interface. No more thumbing through a dictionary, or fumbling through a single-word search; with Lexipedia you can see related words, synonyms, antonyms and fuzzynyms. And best of all, it's absolutely free!
n.
a written explanation or criticism or illustration that is added to a book or other textual material; "he wrote an extended comment on the proposal"