Check is a type of Defend. Check is a synonym of Discipline. Discipline is a synonym of Correct. Correct is a synonym of Reform. 
Bitter is related to Basic. Basic is related to Unit. 
Defend <--IsA-- Check <--Synonym--> Discipline <--Synonym--> Correct <--Synonym--> Reform 
Bitter <--RelatedTo--> Basic <--RelatedTo--> Unit 