The Oxford reverse dictionary - David Edmonds

This dictionary will help you to find the word on the tip of your tongue. Unlike a thesaurus, where you look up alternatives to a word you know, or a dictionary which defines a word you are already familiar with, this "reverse" dictionary will help you to find words you do know, or are vaguely aware of, but cannot bring to mind. There are 31,000 grouped under a wide range of key words. The words listed may be alternative words for the headword, or words that are related to that subject. For example, under "hat" you would find "cloche", "mortarboard", "milliner" etc, each preceded by a short definition. For each sense, there may be more than one example. There are also word groups which are connected by their country of origin; for example, under "Australia", you would find words such as "billabong", "boomerang", and "dingo". Any adjectives and combining forms (suffixes or prefixes) associated with the headword appear first in the entry. Technical words or those used only by specialists in particular fields are not included.