Overwhelm is a synonym of Involve. Involve is a type of Refer. Refer is a type of Classify. 
Round is related to Glass. Glass is related to Stone. Stone is related to Rolling. 
Overwhelm <--Synonym--> Involve --IsA--> Refer --IsA--> Classify 
Round <--RelatedTo--> Glass <--RelatedTo--> Stone <--RelatedTo--> Rolling 