Course is related to Part. Participate is etymologically related to Part. 
Unit is related to Say. Say is related to Whisper. Whisper is the opposite of Cry. Cry is related to Emotion. 
Course <--RelatedTo--> Part <--EtymologicallyRelatedTo-- Participate 
Unit <--RelatedTo--> Say <--RelatedTo--> Whisper <--Antonym--> Cry <--RelatedTo--> Emotion 