Foot is the opposite of Head. Head is a synonym of Commander. Commander is related to Naval. 
Major is related to Liver. Liver is related to Internal. Internal is the opposite of External. 
Foot <--Antonym--> Head <--Synonym--> Commander <--RelatedTo--> Naval 
Major <--RelatedTo--> Liver <--RelatedTo--> Internal <--Antonym--> External 