Pretty is etymologically related to Cute. Cute is related to Beauty. Beauty is related to Winner. Winner is a type of Book. 
Purple is related to Blue. Blue is related to Emotion. 
Pretty --EtymologicallyRelatedTo--> Cute <--RelatedTo--> Beauty <--RelatedTo--> Winner --IsA--> Book 
Purple <--RelatedTo--> Blue <--RelatedTo--> Emotion 