Friend is etymologically related to Free. Free is related to Give. Give is a synonym of Collapse. Collapse is a synonym of Burst. 
Theoretical is similar to Abstract. Abstract is related to Size. Size is related to Attribute. Attribute can be used for Identification. 
Friend --EtymologicallyRelatedTo--> Free <--RelatedTo--> Give <--Synonym--> Collapse <--Synonym--> Burst 
Theoretical <--SimilarTo--> Abstract <--RelatedTo--> Size <--RelatedTo--> Attribute --UsedFor--> Identification 