Stuff is a type of Fill. Stuff is related to Department. Department is a synonym of Specialty. 
Muscle can be used for Walk. Walk is related to Leg. Leg is related to Single. Single is related to Cell. 
Fill <--IsA-- Stuff <--RelatedTo--> Department <--Synonym--> Specialty 
Muscle --UsedFor--> Walk <--RelatedTo--> Leg <--RelatedTo--> Single <--RelatedTo--> Cell 