Do you have the Dictionary application in the Applications folder? Can you find it via Spotlight?
And what does "tolls" mean?
Anyway, I attached the Dictionary.app file in a .zip file, decompress the .zip file and put the extracted Dictionary.app file into your Applications folder if it is gone from there.
If it is not gone from there, try another temporarily created user and see, if you can access the Dictionary from there via right clicking a word, if that is what you do.
Btw, which application do yo use to write the paper?
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