This is one of those tips on Mac, that I really love. Lets say you are reading on Safari (or any other web Browsing) and find the word “Mystical” and you don’t know exactly the meaning of this.
You hit CONTROL + COMMAND + D and move the cursor over the word.
The result, is that a box will appear with the definition of the Word “Mystical”.
After this happen, you will have the option to see the Thesaurus definition, or hit more and open the dictionary application on the mac and see the whole content.