Depression is a type of Mood. Mood is a synonym of Mind. Mind is the opposite of Matter. 
Toy is related to Small. Small is related to Drop. Drop is related to Baseball. Baseball can be Round. 
Depression --IsA--> Mood <--Synonym--> Mind <--Antonym--> Matter 
Toy <--RelatedTo--> Small <--RelatedTo--> Drop <--RelatedTo--> Baseball --HasProperty--> Round 