Pond is etymologically related to Pound. you are likely to find Stone in/at/on Pond. Stone is the opposite of Metal. 
Senator is a type of Legislator. Deputy is a type of Legislator. Deputy is related to Law. 
Pound <--EtymologicallyRelatedTo-- Pond <--AtLocation-- Stone <--Antonym--> Metal 
Senator --IsA--> Legislator <--IsA-- Deputy <--RelatedTo--> Law 