Couple is a synonym of Mate. Mate is a type of Officer. Officer is a synonym of Policeman. Inspector is a type of Policeman. 
Slow is related to Walking. Walking is related to Knee. Knee is related to Lap. 
Couple <--Synonym--> Mate --IsA--> Officer <--Synonym--> Policeman <--IsA-- Inspector 
Slow <--RelatedTo--> Walking <--RelatedTo--> Knee <--RelatedTo--> Lap 