Breakfast is etymologically related to Break. Breakfast is related to Milk. Milk is related to Cake. Cake is related to Sweat. 
Must is related to Atmosphere. you are likely to find Cloud in/at/on Atmosphere. Cloud is related to Phenomenon. 
Break <--EtymologicallyRelatedTo-- Breakfast <--RelatedTo--> Milk <--RelatedTo--> Cake <--RelatedTo--> Sweat 
Must <--RelatedTo--> Atmosphere <--AtLocation-- Cloud <--RelatedTo--> Phenomenon 