Treaty is a synonym of Agreement. Agreement is a synonym of Harmony. 
Hole is related to Break. Break is etymologically related to Fraction. Fragile is etymologically related to Fraction. 
Treaty <--Synonym--> Agreement <--Synonym--> Harmony 
Hole <--RelatedTo--> Break --EtymologicallyRelatedTo--> Fraction <--EtymologicallyRelatedTo-- Fragile 