Bull is a type of Man. Bull is the opposite of Weak. 
Boyfriend is derived from Boy. Boy is related to Deliver. Deliver is related to Birth. Birth is a type of Person. 
Man <--IsA-- Bull <--Antonym--> Weak 
Boyfriend --DerivedFrom--> Boy <--RelatedTo--> Deliver <--RelatedTo--> Birth --IsA--> Person 