Bitter is related to Mouth. Mouth is related to Vocal. Vocal is related to Talk. Talk is related to Oral. 
Policeman is related to Officer. Master is a type of Officer. 
Bitter <--RelatedTo--> Mouth <--RelatedTo--> Vocal <--RelatedTo--> Talk <--RelatedTo--> Oral 
Policeman <--RelatedTo--> Officer <--IsA-- Master 