Secret is related to Trick. Trick is the opposite of Play. Play is related to Rent. 
Laughter is related to Emotion. Concern is a type of Emotion. Concern is related to Matter. Matter is related to Fact. 
Secret <--RelatedTo--> Trick <--Antonym--> Play <--RelatedTo--> Rent 
Laughter <--RelatedTo--> Emotion <--IsA-- Concern <--RelatedTo--> Matter <--RelatedTo--> Fact 