Confusion is related to Lost. Lost is related to Unknown. Unknown is the opposite of Known. Known is a synonym of Appear. 
Foster is a type of Rear. Rare is etymologically related to Rear. Rare is a synonym of Unusual. 
Confusion <--RelatedTo--> Lost <--RelatedTo--> Unknown <--Antonym--> Known <--Synonym--> Appear 
Foster --IsA--> Rear <--EtymologicallyRelatedTo-- Rare <--Synonym--> Unusual 