Thesaurus no longer available in Dashboard

I noticed this morning that my dictionary in my Dashboard was not working. I was able to get it back by clicking on the dictionary app in the finder. When I did this, it said that the app could not open until a new dictionary was installed so I did this. This fixed the problem, or so I thought. But the thesaurus is still not available. When I have the dictionary app in finder open, it appears that all is well. If I click on the "thesaurus" tab, it says to type in a word to look it up in the thesaurus, but when I do this, all I get is the same information that the dictionary provides. I cannot see any option to download the thesaurus part and it seems that I should already have it. I'm using Sierra 10.12.3. I would appreciate any help.