When I wasn’t looking this Website/Mindware got a lot better. Visual Thesaurus is an on-line subscription tool (~$3/month) that you can also buy as a desktop utility, that allows you to put in a word and see its related words visually. I put in play and got back a blizzard of related words,
(Click on the image to see it full size)
Each node can be clicked on to find out what everything radiating from that node shares in common. For example, travel, locomote, go and move all radiate from a common node. Clicking on that brings up a definition that all four share, and an example sentence,
What relationships are shown in the diagram is dictated by your settings (as is font size, line size and many other aspects of the diagram),
You can see that this goes well beyond just synonyms.
The node colors are keyed to the definition chart (thus, the green that tied together the four words above is listed in the verbs section, and all the verb nodes in the entire diagram are defined there as well.
You can reverse the action and find a definition under verb and that will light up the node and thus show you the words associated with it.
Of course, if you click on a word, that word becomes the focus of a new set of associations, allowing you to progress from Play –> Contend –> Debate –>Argument –>Variable->Symbol to Star…
This can be either incredibly rewarding for your writing, or a tremendous time-sink. But it is wonderfully responsive and great fun.