Descriptionary

"Descriptionary: A Thematic Dictionary" is a book written by Marc McCutcheon and published by Facts on File, starting with the first edition in 1992.

Like a normal dictionary, it is used to look up the correct spelling and definition of words. However, words are organized thematically, rather than alphabetically. This makes it useful for those situations where one is trying to find the word for something one has in mind. For example, if someone is trying to remember what the word is for "that red insect with two prongs coming out of its rear", they can open to the section for animals, then to the one for insects, and come to a list of insects, with definitions (the insect in this case is an earwig).