Abstract is similar to Theoretical. Theoretical is the opposite of Actual. Actual is the opposite of Possible. Possible is related to Able. 
Royal is a synonym of Major. Major is a type of Student. 
Abstract <--SimilarTo--> Theoretical <--Antonym--> Actual <--Antonym--> Possible <--RelatedTo--> Able 
Royal <--Synonym--> Major --IsA--> Student 