Contract is a type of Bid. Bid is a synonym of Invite. Invite is related to Invitation. Invitation is a type of Request. 
Exhibit is a type of Evidence. Evidence is related to Court. Court is related to Prosecutor. Prosecutor is a different concept from Defender. 
Contract --IsA--> Bid <--Synonym--> Invite <--RelatedTo--> Invitation --IsA--> Request 
Exhibit --IsA--> Evidence <--RelatedTo--> Court <--RelatedTo--> Prosecutor <--DistinctFrom--> Defender 