Recover is a type of Get. Get is a synonym of Understand. 
Cure is related to Medical. Medical is related to Health. Health is the opposite of Sick. Sick is a synonym of Ill. 
Recover --IsA--> Get <--Synonym--> Understand 
Cure <--RelatedTo--> Medical <--RelatedTo--> Health <--Antonym--> Sick <--Synonym--> Ill 