Metal is related to Lead. Lead is a synonym of Track. Track is a synonym of Rail. 
Baby is the opposite of Adult. Adult is related to Sheep. Sheep is related to Carrier. Carrier is a type of Immune. 
Metal <--RelatedTo--> Lead <--Synonym--> Track <--Synonym--> Rail 
Baby <--Antonym--> Adult <--RelatedTo--> Sheep <--RelatedTo--> Carrier --IsA--> Immune 