Leave is a synonym of Abandon. Abandon is a synonym of Depart. Depart is the opposite of Stay. 
Professional is a different concept from Starting. Starting is related to Declare. Declare is a type of State. State is related to Fair. 
Leave <--Synonym--> Abandon <--Synonym--> Depart <--Antonym--> Stay 
Professional <--DistinctFrom--> Starting <--RelatedTo--> Declare --IsA--> State <--RelatedTo--> Fair 