Barrel is related to Gun. Gun is related to Piece. Piece is related to Column. 
Soft is etymologically related to Seem. Soft is related to Kind. Kind is related to Music. Music is the opposite of Secular. 
Barrel <--RelatedTo--> Gun <--RelatedTo--> Piece <--RelatedTo--> Column 
Seem <--EtymologicallyRelatedTo-- Soft <--RelatedTo--> Kind <--RelatedTo--> Music <--Antonym--> Secular 