Reference is related to Drop. Drop is related to Loose. Loose is the opposite of Exact. 
Hypothesis is related to Idea. Idea is a type of Opinion. Opinion is a synonym of Judgment. Judgment is a type of Trait. 
Reference <--RelatedTo--> Drop <--RelatedTo--> Loose <--Antonym--> Exact 
Hypothesis <--RelatedTo--> Idea --IsA--> Opinion <--Synonym--> Judgment --IsA--> Trait 