Onion is a type of Vegetable. Onion is related to Cry. Cry is related to Fly. 
Opera is related to Soap. Soap is related to Ash. Ash is a type of Wood. Wood is related to Nest. 
Vegetable <--IsA-- Onion <--RelatedTo--> Cry <--RelatedTo--> Fly 
Opera <--RelatedTo--> Soap <--RelatedTo--> Ash --IsA--> Wood <--RelatedTo--> Nest 