Barrel is related to Wood. Wood is related to Club. 
Opt is the opposite of Join. Join is the opposite of Quit. Quit is related to Stop. Stop is the opposite of Let. 
Barrel <--RelatedTo--> Wood <--RelatedTo--> Club 
Opt <--Antonym--> Join <--Antonym--> Quit <--RelatedTo--> Stop <--Antonym--> Let 