Costume is the opposite of Normal. Normal is the opposite of Ill. Ill is similar to Hostile. 
Ground is related to Concrete. Concrete is a type of Cover. Cover is a synonym of Legend. 
Costume <--Antonym--> Normal <--Antonym--> Ill <--SimilarTo--> Hostile 
Ground <--RelatedTo--> Concrete --IsA--> Cover <--Synonym--> Legend 