Domestic is related to Sheep. Sheep is related to Hair. you are likely to find Hair in/at/on Head. Headache is derived from Head. 
Conscience is the opposite of Devil. Devil is a type of Trouble. Trouble is related to Cause. 
Domestic <--RelatedTo--> Sheep <--RelatedTo--> Hair --AtLocation--> Head <--DerivedFrom-- Headache 
Conscience <--Antonym--> Devil --IsA--> Trouble <--RelatedTo--> Cause 