Buyer is the opposite of Merchant. Merchant is a synonym of Dealer. Dealer is a type of Firm. Firm is a synonym of House. 
Enterprise is similar to Venture. Venture is related to Tour. Tour is related to Motor. Motor is related to Battery. 
Buyer <--Antonym--> Merchant <--Synonym--> Dealer --IsA--> Firm <--Synonym--> House 
Enterprise <--SimilarTo--> Venture <--RelatedTo--> Tour <--RelatedTo--> Motor <--RelatedTo--> Battery 