Thin is a synonym of Weak. Weak is the opposite of Power. Control is a type of Power. Regulator is a type of Control. 
Senior is etymologically related to Senate. Senate is a different concept from Congress. Congress is a synonym of Assembly. Legislature is a type of Assembly. 
Thin <--Synonym--> Weak <--Antonym--> Power <--IsA-- Control <--IsA-- Regulator 
Senior --EtymologicallyRelatedTo--> Senate <--DistinctFrom--> Congress <--Synonym--> Assembly <--IsA-- Legislature 