Bucket is related to Liquid. Acid is a type of Liquid. you are likely to find Acid in/at/on Stomach. 
Senior is etymologically related to Senate. Senate is a type of Legislature. Legislature is a type of Assembly. Bench is a type of Assembly. 
Bucket <--RelatedTo--> Liquid <--IsA-- Acid --AtLocation--> Stomach 
Senior --EtymologicallyRelatedTo--> Senate --IsA--> Legislature --IsA--> Assembly <--IsA-- Bench 