Yes.
On your dashboard - go to "Synonyms" tab.
On the left hand you will see the synonyms box - where you can manually add the synonyms as you like. Look closely at the instructions on the page on how to add the synonyms correctly.
On the right side of the page, you will see our Big-data synonyms suggestion table. These are synonyms suggestion tailor-made for your store, according to our database. You may select suggestions here and add to the synonyms table on the left.