Regret is a type of Refuse. Refuse is related to Will. Could is etymologically related to Will. 
Doctor is related to Title. Title is related to Mrs. Ms is etymologically related to Mrs. 
Regret --IsA--> Refuse <--RelatedTo--> Will <--EtymologicallyRelatedTo-- Could 
Doctor <--RelatedTo--> Title <--RelatedTo--> Mrs <--EtymologicallyRelatedTo-- Ms 