Buy is the opposite of Save. Save is a different concept from Waste. Waste is related to Excessive. 
Train is related to Vehicle. Rocket is a type of Vehicle. Rocket is a type of Rise. 
Buy <--Antonym--> Save <--DistinctFrom--> Waste <--RelatedTo--> Excessive 
Train <--RelatedTo--> Vehicle <--IsA-- Rocket --IsA--> Rise 