Someone on Compuserve recommended the One Look Reverse Dictionary.
There are two kinds of reverse dictionary. In this kind, you enter some general phrases to remind you of a specific word.
The díctionary allows you to:
find words from their definition
explore related concepts
create a list of words in a category
answer basic questions (e.g. what is the capital of Vietnam?
solve crossword clues using wildcards
It apparently indexes hundreds of other online reference sites.
I have such a dictionary in print form, dated early 1990s.
Reader’s Digest Reverse Dictionary, 1989, ISBN 0 276 49541 1
Bizarrely, this was ‘translated’ into German:
Der schnelle Weg zum richtigen Wort, ADAD-Verlag, 1992, ISBN 3 87003 473 4
There are also reverse dictionaries that classify words by their endings, so that a group of words ending in ‘erely’ will be together.
Is there one of those online? There must be. All I have is a GDR one, Martin Lehnert’s Rückläufiges Wörterbuch der englischen Gegenwartssprache, VEB Leipzig 1971. The first three words are a, baa, sahaa, and the last buzz, abuzz, fuzz.
LATER NOTE: For those who found this information exciting, I must say I discovered I have already blogged it: my mind must be going.
STILL LATER NOTE: As Abnu points out in the comments (in a discussion as to which of us has not had enough coffee today), the OneLook dictionary can be used to find patterns and thus does the work of a rückläufiges Wörterbuch. Here are the results of a search for *nch.