Add is related to Calculation. Calculation is related to Division. Division is related to Degree. Degree is related to Small. 
Button is etymologically related to Butt. Butt is a synonym of Ass. Ass is related to Association. 
Add <--RelatedTo--> Calculation <--RelatedTo--> Division <--RelatedTo--> Degree <--RelatedTo--> Small 
Button --EtymologicallyRelatedTo--> Butt <--Synonym--> Ass <--RelatedTo--> Association 