Invisible is related to Electricity. Electricity is a type of Energy. Energy is related to Meaning. Meaning is related to Peace. 
Degree is related to Accomplishment. Accomplishment is related to Possible. Possible is the opposite of Unable. 
Invisible <--RelatedTo--> Electricity --IsA--> Energy <--RelatedTo--> Meaning <--RelatedTo--> Peace 
Degree <--RelatedTo--> Accomplishment <--RelatedTo--> Possible <--Antonym--> Unable 