Economics is related to Business. Business is related to Division. Division is related to Century. Century is related to Period. 
Skin is etymologically related to Shed. Skin is related to Flesh. Flesh is related to Fruit. 
Economics <--RelatedTo--> Business <--RelatedTo--> Division <--RelatedTo--> Century <--RelatedTo--> Period 
Shed <--EtymologicallyRelatedTo-- Skin <--RelatedTo--> Flesh <--RelatedTo--> Fruit 