Discussion is a synonym of Conversation. Conversation is related to Listen. Listen is the opposite of Say. 
Sign is related to Indicator. Indicator is related to Price. Price is related to Pay. Pay is a synonym of Fee. 
Discussion <--Synonym--> Conversation <--RelatedTo--> Listen <--Antonym--> Say 
Sign <--RelatedTo--> Indicator <--RelatedTo--> Price <--RelatedTo--> Pay <--Synonym--> Fee 