Burst is a synonym of Collapse. Collapse is a synonym of Give. Give is related to Free. Friend is etymologically related to Free. 
Shirt is etymologically related to Skirt. Short is etymologically related to Shirt. Short is a synonym of Flat. 
Burst <--Synonym--> Collapse <--Synonym--> Give <--RelatedTo--> Free <--EtymologicallyRelatedTo-- Friend 
Skirt <--EtymologicallyRelatedTo-- Shirt <--EtymologicallyRelatedTo-- Short <--Synonym--> Flat 