Song is related to Length. Length is related to Measurement. Measurement is a synonym of Calculation. 
Opposite is a synonym of Reverse. Reverse is a type of Side. Side is related to Swim. Swim is related to Free. 
Song <--RelatedTo--> Length <--RelatedTo--> Measurement <--Synonym--> Calculation 
Opposite <--Synonym--> Reverse --IsA--> Side <--RelatedTo--> Swim <--RelatedTo--> Free 